I heard the first message on my cell phone as I was driving home from dinner with a friend. It was from a guy named Peter, a Dutch tour guide whom I had met more than three years before in the Moroccan desert -- a random encounter that had lasted perhaps an hour, over a couple of beers at an auberge in remote Todra Gorge. My first thought was: How did Peter get my cell number, and why was he calling me now?

When I got home, there were two more messages from Peter on my answering machine, the first reminding me about our meeting at Todra Gorge and the second saying: "Please listen to me. I want to speak to a journalist because something is going to happen very bad."

It was nighttime May 24 in Bolton, Miss., where I live, about 4 a.m. in Amsterdam, Peter's home. When I called the number Peter had left, he answered immediately. His voice sounded agitated. "Alan, there's going to be something very, very bad, even more than happened in New York a few days, I mean a few years ago," he said. His English seemed to be failing him, and he said he would call back on a different line.

During two follow-up calls that night, in language that was at times maddeningly cryptic, Peter warned of a planned terrorist attack in New Orleans that would take place within the next three weeks. "It's going to be much worse than 9/11," he said. He claimed that instead of being a tour guide, he actually worked for CIS, a private Dutch ship inspection agency, but he had recently quit his post after agency officials refused to act upon his New Orleans tip, which he said originated from a terrorist cell operating in Morocco, Tunisia and Algeria. He said he had contacted me because I was the only American journalist he knew. He knew that I had written for newspapers and magazines and that I was working on a nonfiction book.

I had no idea what to make of Peter's warning. I couldn't help thinking of the deluded guy who once repeatedly called a reporter I knew, insisting that the reporter come over to his house "to see the pony that Reagan left in my yard." But I felt obliged to pass the information along to someone, so I called the local sheriff, Malcolm McMillan, that same night and told him what Peter had said. "What would you do with this kind of information?" I asked McMillan. He said he would have someone call me, although he wasn't sure who it would be.

While I was waiting for the sheriff's call, Peter called again. This time he went into greater detail. He said he was "100,000 percent sure" that something would happen in Louisiana. I asked why he had not passed the tip along to authorities in the United States, and he said: "I don't want any part of the system. I'm just going down under . . . I can disappear . . ." I could hear another man's voice in the background. Peter said he was packing his bags, that he planned to "go over to the other side." I asked if he meant to the terrorist side, and he said, "No. You must know what I mean." When I said I did not, he repeated: "I will be on the other side. Don't see the other side as the side which is aggressing you. See the other side when your foot is down, it will be on my foot." Then he added, "Maybe you will hear from me next week, or maybe you will never hear from me again."

The next time the phone rang it was Keith Moses, an agent with the Jackson, Miss., office of the FBI, who listened to my account, asked a few questions and then said he would call back the next day. The investigation had begun.

The FBI gets countless tips, and sorting truth from lies and fever dreams is a gargantuan task. People tend to see goblins everywhere these days, and not without some justification. Terrorists sometimes take advantage of this widening paranoia by leaking erroneous information to confuse intelligence agencies and cause them to waste manpower -- a kind of terrorist "noise." I had no idea how Peter's call might fit into the mix, if he really worked for CIS, if he was delusional, or if he was perhaps a terrorist operative himself, trying to manipulate me and whomever else I might infect with his story. Anything seemed possible. But this much was clear from the tenor of Moses's questions: Peter's warning had assumed a life of its own. In the coming days, it would throw open a window upon a strange, murky world of threats and counterthreats -- a world that we will likely inhabit for the rest of our lives, yet now know very little about.

ABOVE THE TERRACE OF THE AUBERGE TOMBOUCTOU, the sky was so bright with stars that I could make out the faces of the camels tethered to palm trees 100 feet away. It was September 2000. A couple of local guys played nomad drums in the lamplight, as much for themselves as for the guests, who included me, my friend Josh Zimmer and a boisterous group of German tourists and their Dutch guide, Peter.

This is my first memory of Peter: As an annoying intrusion, a man who took advantage of a break in the drummers' performance to lead his German charges in an off-key, beer-hall rendition of "American Pie." Other bad American pop tunes followed. I made a mental note to try to expunge the group from my memory of the place, a small Moroccan oasis known as Merzouga.

As Josh and I sat on the terrace that night, the drumming of the local musicians was so strong that it resonated through our chests, rhythmic and hypnotic. The Auberge Tombouctou, an inn set against a backdrop of orange dunes that are the tallest in Morocco, is a popular stop for trekkers getting their first taste of the Sahara Desert. The Algerian desert has never been a hospitable place but was then, and still is now, truly off-limits because of internal and international political disputes and a dangerous proliferation of machete-wielding bandits and rebels with guns and four-wheel-drives. Merzouga, which was once a stop for caravans, is hemmed in and subsists primarily on a few small herds of camels and goats, a rug shop belonging to a gregarious and photogenic merchant named Brahim Karaoui, and the inns and guide services used by trekkers and the occasional movie crew.

Aside from a few satellite phones and electric generators, Merzouga was remote and exotic. The staff of the Tombouctou managed to provide an environment that was seductive to such people as were gathered on the terrace on that particular night. The drummers got to play their traditional music and make a little money by selling cassettes. Because of the tourists, they felt less compelled to move to Casablanca or Tangier in search of jobs.

Although we did not know it then, everything would change the following year. Ironically, the drummers, the staff of the Tombouctou and Brahim would begin to lose their hold on their gainful traditional life because of the actions of fundamentalists bent on eradicating modernism from the Islamic world. On September 11, 2001, terrorist attacks in the United States would cause the tourism economies of Morocco and many other Muslim countries to sharply decline -- a side effect of fearpartly by terrorist design.

Tourist-dependent Islamic countries are inevitably more secular and Western-friendly, and terrorists are aware that by undermining those economies, the governments are made vulnerable. For a millennium, trade has brought an endless parade of outsiders across Morocco's borders, and, as a result people tend to be tolerant of, and in many cases attracted to, cultural differences. It is not unusual to meet people, such as Brahim Karaoui, who speak several languages.

Morocco's atmosphere of openness then belied a strong undercurrent of fundamentalist intolerance and dissent, which would break the surface after 9/11. But on that evening, most of us on the terrace of the Tombouctou were blissfully ignorant of what lay ahead, with the possible exception of Peter.

To our dismay, we again encountered Peter and company a few days later in Todra Gorge, a narrow chasm knifing into the Atlas Mountains several hours west of Merzouga. This time, after sharing a few beers with him, we found he had an odd charm. Dressed somewhat affectedly in a green djellaba -- the traditional robe of Moroccan Berbers -- he talked expansively about Islamic culture, of which he was quite enamored. He was fluent in Arabic. By the next morning, when Josh and I departed Todra Gorge aboard a hired, ramshackle Datsun piloted by an angry and confused maniac -- "the death ride down the mountain," as Josh described it -- I had Peter's e-mail address. As often happens after these sorts of encounters, we exchanged a few e-mails before slowly losing touch. I received a message from him after 9/11 in which he lamented the attacks, and we tried, unsuccessfully, to hook up when I later visited Amsterdam. But it would be a little more than three years before I would hear his nervous voice on my answering machine.

MEETING PETER SEEMED AN INSIGNIFICANT EVENT AT THE TIME, but that was not the case when I met Brahim Karaoui. Meeting Brahim was one of those encounters where you recognize a kinship instantly. Our resulting e-mails brought us closer. In the years since 9/11, I have come to see our friendship as an antidote to the fear and chaos into which the world seems to be descending. When I hear Americans railing against Muslims on Fox News, when I read about a young Arab wrongly incarcerated at Guantanamo, when I consider the growing division between Islam and the West, I think of Brahim.

There is one incontrovertible fact of life about touring Morocco: Like it or not, at some point you are going to end up in a rug shop. If you hire a guide, converse with a stranger or simply ask someone for directions, you are almost certainly going to find yourself in a rug shop belonging to someone's friend. Sometimes the guide will make a commission; sometimes it is done as a favor to the rug merchant or to you, but the visit itself is not really negotiable. At first the experience is interesting and the subtle battle of wits engaging. You sit on pillows sipping sweetened mint tea, smoking if you like, while boys in turbans roll out rug after rug for you to judge. After a while, you notice that you are finding more and more rugs attractive, because the merchant is observing closely, watching your face, your reactions, triangulating and making his selections accordingly. There is something almost sexy about the exchange. Soon more of the rugs have that nice blue rectangle that you like, and before you know it, you are as determined as the merchant to find the perfect rug that dwells inside of you.

But eventually the ritual grows tiresome. By the time we got to the desert during that trip in 2000, we told our guide, Mohar, that we would tip him extra if he could somehow muster the will to leave rug shops off our itinerary. We thought we had a deal. Then, as we were motoring through Merzouga in his Land Rover, Mohar slowed to a stop and said he needed to speak with a friend. Did we want to meet him? By then we had let down our guard, and we walked into a carpet shop ambush.

We were annoyed to see the stacks of rugs, and there seemed no reason to stand on ceremony. I informed Brahim, the shop's owner, that we had no money to spend, that he could show us the different patterns and explain their meanings, could point out the fine craftsmanship, tell us the story of this particular Berber tribe or that particular weaver's life, but that there would absolutely be no sale. He smiled and said: "No problem. We have some tea, talk about life." And so we did. I remember Josh's incredulous glance when he saw me giving Brahim my credit card. I had found a rug I liked. Soon Josh had opened his backpack, and he and Brahim were going through his things, looking for items that Brahim might accept to augment the money Josh was willing to pay for his chosen rug.

After completing the transactions, we lingered in Brahim's shop. He had a great wit. At some point, he decided to close the shop and travel with us for a few days, and soon we were barreling across the flat desert at interstate highway speed, headed for Todra Gorge with him. Although Brahim's English was rudimentary, and we spoke no Arabic, we managed to communicate surprisingly well, and the conversation quickly expanded from basic personal histories to encompass our dreams for life and our surprisingly similar views on the ways of the world. During a sunset hike through Todra Gorge, we posed together for photos in which Brahim unfurled part of his turban and wrapped the loose end around each of our heads, so that we were linked. Brahim left us before we met Peter. Josh and I returned home, but our e-mails with Brahim didn't fade away, and when Brahim came to the United States on business, we traveled with him.

After 9/11, the tourists who were Brahim's livelihood stopped visiting Merzouga, and he decided to ship 60 rugs to my Mississippi home to hold a private sale. His anticipated arrival was a bit unnerving, under the circumstances, and I gently tried to explain before his trip that under newly passed laws, he could be arrested at the Atlanta airport without clear cause, without being charged or even given access to legal counsel, and without being given the opportunity to notify me. He dismissed my concerns, saying he was on our side, that he hated the terrorists, that they did not represent Islam and that they were murderers. He believed his affinity for the United States would protect him. I was not so sure, and, as it turned out, he was questioned by customs officials for about hour at the airport. But, otherwise, there were no problems.

At the rug sale, he played cassettes of Berber music, served mint tea and charmed everyone with his friendliness and humor. The rugs moved.

As the world situation continued to deteriorate, Brahim, Josh and I made a pact to continue our travels together, through the United States and various Muslim countries. Last September, we met in Istanbul, where Brahim enjoyed the attention he attracted while walking arm in arm with two Westerners. A month later, Istanbul was rocked by terrorist bombings.

In our visits and e-mails and over the phone, Brahim and I rarely talked politics. When we did, we almost always agreed. Neither Bush nor bin Laden represented us. But as more and more international attention became focused on Moroccan terrorists, our dialogue became more circumspect. "Terrorism knows no nationalities," he sadly noted in one e-mail. In May 2003 there was a terrorist bombing in Casablanca; in March, Moroccans were implicated in the Madrid train bombings. Brahim could hardly bear to discuss it, all of which contributed to my reluctance to tell him about Peter's calls. I did not want to burden him with the news, and in my borderline paranoia, I was afraid someone might intercept my e-mail and somehow wrongly implicate him. I could easily imagine him being picked up for interrogation, even though he knew nothing about it. Stranger things have happened, and in fact, seemed to be happening now.

THREE DAYS AFTER PETER CALLED, and after I had spoken with FBI investigator Moses numerous times on the phone, I met with agents Victor Mason and Kevin Sanderson. Both took notes. Sanderson asked for all my phone numbers, including my fax, every address associated with me, my Social Security number and my professional activities. He wanted an account of my relationship with Peter and my take on what Peter had said and why he had contacted me. I could not offer much. I had no way of knowing if any of what Peter had said was true. Sanderson asked if I had tried to contact Peter since the initial calls. I said I had, unsuccessfully, but I still had his voice-mail messages, if that would help. Sanderson said perhaps Peter's warning was a diversion, but nonetheless, Moses said, the FBI had issued a nationwide bulletin about it. When Moses stuck his head through the door of the room, where Mason and Sanderson were interviewing me, I asked if I could see the bulletin, but he said no. "You'll probably see it on CNN at some point," he said. "That's what we usually see happen."

Toward the end of the interview, I told Sanderson: "I know you're going to be checking me out, and you should be. I would if I were you. So one of the things you're going to find is that I sometimes wire money to Morocco. I want you to know that in advance." I told him about meeting Brahim and how I had been helping him sell rugs in the United States. When the gallery where I had placed his remaining rugs made a sale, they sent me a check, and I wired the funds to Brahim. Sanderson asked me to spell Brahim's name, and I had a sinking feeling. Brahim may represent all that is good in the Islamic world from my point of view, but I had mentioned him in the context of Peter's call, and he was now duly noted in a terrorist investigation. He and Peter shared space in Sanderson's notes. Sanderson asked if Brahim knew Peter. I said I did not think they had met.

How does anyone know what is true in a case like this? Who knows what anyone's agenda is? The situation opens many opportunities for error, for locking up innocent people among suspected terrorists in Guantanamo. The fact that so many of my friends had asked that I not send e-mail to them about Peter and the FBI was evidence that many Americans realize the boundaries have changed. Fear is like a virus: It just grows, fed by controversial elements of the USA Patriot Act, which gives the executive branch greater power to conduct wiretaps and searches in secret and allows law enforcement agencies to share more information.

Once you begin to seriously question things, it is surprisingly difficult to stop. Was I wasting time or doing something important? Had my normal citizen's impulse made me suspect? Had my words implicated my friend? No Arab Muslim wants to be on an FBI list, because even if he is entirely innocent, being noticed carries the potential for dire consequences. Clearly, trouble can be just a phone call away.

In my conversations with the FBI agents, they made clear that they appreciated the tip and would pursue it aggressively. Tips from the public are crucial in combating terrorism, even if the interactions between the informant and law enforcement officials can become awkward. Yet because of my uncertainty about where the investigation might be headed, I felt obliged to e-mail Brahim and tell him everything. I heard back a few days later. "I am very sorry to have started speaking about terrorism," he wrote. "I prefer not to speak any more about that, neither look at the news these days, as all we are getting is misery." We agreed not to discuss the matter further, and I tried to reassure him that no trouble would come to him as a result of the investigation.

With that, I went back to trying to decipher Peter's riddles. During one of our conversations, Peter had claimed that an initial event would take place within 72 hours but that the actual attack would come in two to three weeks. A ship would be involved, but no plane. Low-level employees were already in place to help carry out the plan, which was the brainchild of a group known as al-Rashid. He said he had also known about the attack planned for 9/11, but not all of the details, including the date.

The day after his call, a story ran on the wires about a suicide bombing that killed Izzedin Salim, the head of the Iraqi Governing Council in Baghdad; according to news reports, a group calling itself the Arab Resistance Group-al-Rashid Brigades claimed responsibility. Was this the predicted 72-hour event? But no, at the time Peter called, the assassination had already occurred -- perhaps reading the newspaper was where Peter had gotten his "tip."

On the following Friday, the first full day since Peter had called passed without my hearing from the FBI. I hoped that perhaps they had found evidence that Peter was a crackpot. But late in the afternoon, I got a call from the FBI's Mason. After a few pleasantries, he said, "We sometimes do this up here on Saturday, and I want to ask if you'd come down and take a polygraph test." I hesitated for a moment, then said, Sure, no problem. We spoke again a short time later, and I asked if I could tape the interview, but he said he was not sure. "You're not a suspect," he said.

WHEN 5 O'CLOCK SATURDAY EVENING ROLLED AROUND, I entered the dark vestibule of the federal building in Jackson with agents Mason, Moses and Joe Edwards from New Orleans, the polygrapher. We bypassed the metal detectors. Edwards did most of the talking. He was friendly, said he understood if I was nervous because he had taken numerous polygraphs and they always unnerved him. I asked about recording the interview, but he said that no one would be recording it, including them.

On the 15th floor, we entered the exam room, and on a desk between two office chairs was a monstrous-looking apparatus, which turned out to be a somewhat antique polygraph machine. It had an assortment of dials, an armature and ink needle for inscribing the graph, large wires attached to something like electrodes, and surgical-looking tubes. The paper printout bore the scribbles from a previous interview, and, below that, my name, written in longhand. Edwards looked at my face and laughed. He said that he works a lot in Bogota, Colombia, and that when power supplies are unreliable, his old machine performs better than high-tech digital equipment. The other guys still make fun of it, he said.

He began preparing me for the exam, saying that it would not be entirely pleasant, that the point was to get me to lie even before the test begins, to observe my reactions, which he would compare with those from the actual test. He was telling me beforehand, with complete confidence, that he was going to get me to lie. He said, "I know it's kind of insulting." He had me sign a couple of waivers.

We made small talk. He told me he had thrown out his back earlier in the day while tying his shoe. He said he was in a great deal of pain, and added, only half-jokingly, that if he fell to the floor screaming I should call for Moses. I imagined the agents rushing into the room to find Edwards writhing on the floor and me standing above him. Because of his back pain, he said, he might conduct the interview standing up. Then he sat down. He went through a few preliminary questions: Had I ever been arrested? Do I drink too much? Had I ever fabricated a story or even a quote? He mentioned scandals involving journalists who falsified stories, and I said the closest I had come was occasionally filling in a partial quote with words that I thought someone had used but had been unable to write down quickly enough. He said, "I do that all the time."

Really?

I said it occurred to me that the FBI might think that I fabricated Peter's warning to gather material for a story. He nodded. The possibility had been considered, he said, but it did not seem plausible to him because my story was so riddled with holes. When someone is lying or making things up, their stories tend to be complete, he said.

Anyway, I said, if there is any question about whether I made this up, there were always the voice-mail messages. His face registered slight surprise. Midway into our provocative little verbal dance, the music seemed to have stopped. He said, "You have voice-mail messages?"

I nodded. "I told the guys that on Thursday."

He sat stiffly in his chair, staring at me, then said: "Damn. They didn't tell me that." The polygraph was to be a mechanism for validating my story, he said. Suddenly it was not necessary. "I don't think there's any problem with me telling you this, but we found the guy, and he denied talking to you." This was certainly an interesting piece of news. I asked where they found Peter.

"In Holland. They did a great job of finding him," he said.

"So he didn't leave," I said, and asked if Peter actually worked for Dutch intelligence.

"I can't say, but it's likely they wouldn't verify either way," he said.

Edwards then asked me to retrieve one of the voice-mail messages and play it on the speaker phone, and there was Peter saying he's the guy from Todra Gorge. Edwards shook his head. He stood up slowly, said he needed to talk with Moses. He was not happy.

When Edwards and Moses returned, I retrieved the message again on the speaker phone. Moses asked a few questions, then left to make a phone call. I asked Edwards for his gut reaction to all of this. He said: "This guy is probably a flake. But that doesn't mean it's not serious. A lot of these guys are flakes."

I asked if my home phone was being tapped. He said that he did not know but that I could consent to install a listening or a recording device on my phone, in case Peter called again. For the next 15 or 20 minutes, the agents searched the FBI offices for a recording device for me to install on my phone. They came up empty. Edwards thought he had one in his car in the parking garage, so Mason accompanied him to retrieve it. But when Mason returned, he had forgotten it. Something seemed to be ever-so-slightly breaking down. Moses then asked if we could catch Edwards before he headed back to New Orleans, and Mason said sure. It turned out that Edwards was stuck in the parking garage, unable to open the garage door.

Moses looked exasperated. We had stopped in his office, which was an avalanche of boxes and files waiting to happen. He had a refrigerator, which suggested he spent a lot of after-hours time there. Mason had a copy of the Koran and a beginner's guide to Islam on his desk next to his family photos.

We took the elevator down to the garage, which was eerily empty but for Edwards standing beside his Chrysler at the closed steel doors. The sound of our footsteps echoed from the concrete walls.

Edwards handed me the recording device, and Moses pushed hard on the button for the door, which rose noisily. We shook hands, said goodbye. With a supposed three-week window before an attack, the FBI had spent five days trying to determine whether I had actually received a call from Peter. In two more days, the Homeland Security Department would issue a new terror alert, warning of a planned summer attack in the United States, the result, they said, of a continuous stream of terrorist chatter and noise. (Weeks would pass, and there would be no attack in New Orleans, but the urgent sense that terrorists intend to strike the United States before the November election remained.) The following day, Moses called to say that the FBI tried to contact Peter again but that he was nowhere to be found.

I HAD NO FURTHER CONTACT WITH THE AGENTS until the next week, when I was sitting at an outdoor coffee shop in downtown Jackson with another journalist. I told him about Peter's call and how the FBI was handling the tip. We had been talking for perhaps half an hour when -- in what seemed a remarkable coincidence -- I saw Sanderson and Mason approaching our table. Sanderson did not smile. He said, flatly, "Please come with us." I felt a tiny, unexpected flush. I noticed the three women who had been smoking at the next table scurrying away. We followed Sanderson to the center of the courtyard, where he stopped. "I'm not saying you shouldn't talk about this," he said, "but you should watch what you say in public."

I was confused. How could they have heard anything that I had said, and what difference would it make?

Sanderson said the women at the next table worked at the U.S. attorney's office and had reported overhearing two men, one of whom "looked Middle Eastern," talking about a terrorist attack. My ancestry is primarily Scotch-Irish. My friend's family originally came from Poland. Sanderson said the women were perhaps mindful of the recent terrorist alert. Then he added, "I thought it might be you."

I was thinking: Three strangers just fingered me as a possible terrorist, and within a short time two FBI agents were dispatched, and one of them just said, "I thought it might be you." All because of a random conversation three years ago in Morocco. If this could happen to me, what might it mean for Brahim, who lives in what is essentially a totalitarian state bent on proving its alliance with the United States in the "war on terror?"

Sanderson said again that I should be aware of who is listening. Then he and Mason headed back toward the federal building.

I pictured the women from the adjoining table back at the U.S. attorney's office, lording their little drama over their co-workers. The one with the lion's mane of spray-netted hair had glanced purposefully at me when she briefly left the table, no doubt trying to memorize my face. It was silly, an overreaction, but I couldn't really blame her, because in this world, you never know.

Alan Huffman is a freelance writer. His most recent book is Mississippi in Africa.