-- It is fair to say that outlaw biker Donald "Red Dog" Jarvis is freaking the squares at his neighborhood Denny's, the moms and pops with their kids sitting at the nearby tables, suddenly just staring at their waffles and trying very hard to avoid eye contact with Jarvis as he explains why it would have been wrong to whack Billy Queen.

"We're not stupid people. We have rules, you know, we have . . ." -- Jarvis searches for the word -- "we have policies."

About killing? "Especially," Jarvis says.

Jarvis is built like a gladiator, straight out of C-Block, his arms crawling with tattoos, his eyebrow and lip pierced. He just doesn't seem like the kind of person you ask to lower his voice, especially when the former sergeant-at-arms of the San Fernando Valley Chapter of the Mongols, the notorious motorcycle gang, is talking about Queen, a subject that still seems to agitate him. "I was suspecting him of being a cop from the very beginning," Jarvis says. "I just knew it."

And as it turns out, Red Dog was right. William Queen was an undercover agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). For two years, he burrowed in, almost as deep as you could go, becoming, as Queen puts it, "as bad as the baddest of the bad."

The lawman grew a castaway's beard, neglected his personal hygiene, rode stolen Harleys, got bombed in biker bars and brawled with Mongols named Lucifer and Bucket Head by his side. He not only hung with the Mongols, he also formally joined the club, first as a "prospect" (akin to a pledge in a fraternity from Hell) and then as a "full-patched" member, eventually rising through the ranks to be named his chapter's vice president.

The undercover operation, billed by ATF as its most successful penetration of a motorcycle gang, resulted in dozens of successful prosecutions of Mongol members -- for dealing drugs, stealing motorcycles and carrying firearms -- including Jarvis. He pleaded guilty to being a felon in possession of a gun and spent 30 months at a federal correctional institution, "the last 90 days," he offers, "in the hole," also known as administrative isolation. (No big deal, Jarvis says. "They'd pegged me as a shot-caller.")

It would not be unusual for an outlaw biker such as Red Dog (even one who now says he is reformed, has kicked his heroin habit, dates an accountant, listens to Air America talk radio and makes a middle-class living driving his own 18-wheeler) to dislike the cop who nailed him, especially an undercover agent and one whom many Mongols considered a blood brother -- until the day they were taken down, on May 19, 2000, in scores of raids in four states by more than 675 sheriff's deputies and ATF agents.

But this is L.A., babe, and so naturally this story just gets weirder.

While his former Mongol associates were still in prison, Queen retired from the ATF and published a book about his adventures called "Under and Alone: The True Story of the Undercover Agent Who Infiltrated America's Most Violent Outlaw Motorcycle Gang." It reached bestseller lists this summer.

The book describes the Mongols as the worst of the worst -- beer-breathed, meth-snorting, misogynist marauders who lived by a code of fierce loyalty to their brothers -- and to hell with the rest. Their motto: "Respect few, fear none." In the book, Queen's chief antagonist is none other than Red Dog.

Guess what? The Mongols dug the book, or at least parts of it. "I hear they were overjoyed," Queen says. "The more violent and hard and mean you call them, the happier they are." The subjects themselves are a bit less effusive. "The book was okay," concedes Richard "Rancid" Clayton, a talented tattoo artist and a Mongol who went down on gun charges. "But a lot of it was embellished or switched around or wrong." (Like him never showering, Rancid says: "We all took showers. They called me Rancid because I had a dirty mouth. He didn't know that.")

But wait: It gets better. While the book was still in draft form, Queen's agent showed it to a pair of screenwriters, who pitched the idea to Mel Gibson and his company, Icon Productions, whose last big feature was "The Passion of the Christ." Gibson bit, and Warner Bros. Pictures bought the rights and will distribute the film; Antoine Fuqua ("Training Day") is slated to direct.

The role of Billy Queen has not yet been cast (Gibson was initially going to star, though that now appears unlikely, according to Icon) nor have the actors who will play the gang members. But one thing appears certain: The real Mongols want in on the action and have been taking meetings with the filmmakers. They've been bitten by the bug.

The bikers say they will likely be employed as consultants and will probably end up in the movie as extras -- or possibly in more substantial roles. (Fuqua likes the real thing: In "Training Day," about a rogue Los Angeles cop played by Denzel Washington, Fuqua hired actors and extras from the talent agency called Suspect Entertainment, whose ranks are filled with former gangbangers.) "The movie people are going to use Mongols," Queen says. "And the Mongols are as jazzed as they can be."

"We want to use them," says Ned Zeman, a Vanity Fair correspondent who wrote the screenplay with his writing partner Daniel Barnz. "There's no reason not to. Only Mongols look like Mongols." Several of the bikers, fresh out of prison, have been offering their services and have sat down with Fuqua and the Icon producers. Zeman, who has met with some of them, says, "We thought the Mongols would be more reluctant, but they're not." Just the opposite: They're into it.

Ah, Hollywood, where yesterday's Most Wanted by the feds become tomorrow's Most Wanted by E! Some of the bikers are working on their own projects and have been seeking agents to represent them. From three years in the slammer to 15 minutes of fame. The Mongols don't mind being portrayed as violent and mean, Zeman says. "They said just don't make us look like wimps."

No worries. In his book, Queen describes the Mongols and their archrivals the Hells Angels as "sophisticated, calculating, extremely violent -- nothing less than the insidious new face of global organized crime." He also asserts that they have begun to resemble "international terrorist organizations." And clearly, when the ATF announced Queen's undercover work and the bureau's big bust of the Mongols, it wanted the public to feel relief that the fiends were off the streets.

But here's the rub: In both an interview and his book, Queen can't quite support the premise that the Mongols are al Qaeda on two wheels. During his time with them, Queen portrays the San Fernando Valley Chapter of the Mongols as down to its last half-dozen members (nationwide there were about 300), and overall the Mongols seem to spend most of their time drinking, fighting, drugging and riding their motorcycles. They don't really seem like a major threat to society -- unless a citizen goes to one of their bars and propositions one of their "old ladies."

True, they stole motorcycles and had a fondness for firearms -- including the odd machine gun. They dealt weed and speed, but it was nickel-and-dime, and mostly to feed their own appetites, which were hearty. One of the group was convicted on a murder charge, and at one point, members were allegedly planning to gang-rape a couple of strippers (the women, to Queen's great relief, never showed up). So they were bad men. But the government never did bring federal racketeering charges against them. An international cartel? In the San Fernando Valley Chapter, Queen -- whom they knew as Billy St. John -- was the only one who had a credit card (which he used to rent a truck for them).

"Billy Queen tries to make us seem worse than we are," Jarvis says. "Like we're domestic terrorists? Come on."

But there is no denying that Queen walked a dangerous line while undercover.

"What sets them apart is their penchant for violence," says Queen, who survived one knife fight and wicked bar brawls with the Mongols. "It's always there."

Queen, 55, is now a minor celebrity in law enforcement circles, and he regularly does the rubber-chicken convention circuit, regaling prosecutors and cops with his experiences. Although Queen is retired from the ATF, the feds still remain concerned about his safety and Queen himself is wary of retribution from the bikers or their associates -- so much so that he continues to live in an undisclosed location. When he met a reporter to talk about the Mongols and the movie, he picked him up at the Van Nuys airport in his small private plane and flew him to the outskirts of L.A. to have lunch at an airstrip. Queen brought along a briefcase. Inside? His .45. "Never leave home without it," he says.

For all the bad the Mongols do, Queen seems to like them. He grew up, he says, "in a not-so-great neighborhood" in North Carolina. His father chased moonshiners for the ATF. Young Billy boxed as a kid. A Special Forces Vietnam vet, Queen has spent his adult life in law enforcement, first as a city cop, then a Border Patrol officer, and finally an ATF agent. But he didn't like working cases from his cubicle and spent long periods as a street agent or undercover, infiltrating neo-Nazi skinheads, the Aryan Nation and the KKK, and culminating in his two years riding with the Mongols. He says that if he had tried to infiltrate NASA's Jet Propulsion Laboratory, for example, "I'd be caught immediately." But the Mongols? Queen says it got him in touch with his inner Genghis Khan. "Where I feel like I can be as mean and as violent as anyone."

When relating his stories, Queen often enters a realm of role-playing, where his eyes get squinty and crazed, and he starts poking his finger in your chest and threatening you with a string of obscenities. It is disturbing in that he seems to be able to turn it on and off, like an actor, which in a sense he is.

To join the Mongols, Queen used a well-developed and deep undercover identity -- complete with an apartment, a borrowed Harley, a job, a phony driver's license, a back story and other agents to impersonate former employers or family members, because the Mongols hired a private investigator to check Queen out before inviting him to join. (He also had to fill out an application; it is, after all, a club, with a constitution, five commandments and a fight song, whose lyrics can't be printed here.)

Queen got his introduction to the Mongols through a woman, a 200-pound methamphetamine addict and confidential informant with a grudge against the gang who was looking for some payback. Over the next year, over many, many beers, Queen moved up in status from fellow barfly to "hang-around" to prospect and then to member.

As he recalls that time, he describes being the subject of constant challenge -- that he was either too weak to be a Mongol or he was a cop. "You have to be able to kill," he says, "in protection of the pack. That's their bottom line."

At one point, while on a rally to Laughlin, Nev. -- later the scene of a murderous rumble between Mongols and Angels that left three dead and the floor of Harrah's casino trashed -- Queen was challenged to snort a line of speed. As he describes it, the undercover agent was able to pretend to inhale the powder while he wiped it off the table onto the motel carpet.

Queen says he is often challenged on this point: How could he have ridden with these guys for so long and not committed any crimes, especially involving drugs? Luck and skill, Queen says. He'd beg off getting high, saying he was already drunk. He'd claim that since his chapter president was on parole and abstaining, then he, too, would forgo. Queen says that if his life was in danger, ATF rules would allow him to do the drugs but then consider it an on-the-job injury. He'd go to the hospital for treatment. And if he had done drugs and not told his supervisors? "I was subject to random drug testing like every other agent, and if I'd been caught, I'd be fired," he says. The ATF agent who worked most closely with Queen on the investigation did not return phone calls and ATF supervisors were not available for comment.

One of the themes in the book and in the screenplay is how seductive Queen found some of the Mongols and their lifestyle. In his telling, Queen smiles with the memory of a ride across California, with a hundred Mongols on motorcycles roaring down the road, running through traffic lights. "It's just an awesome scene," he says, "this show of raw power. Here are these guys who just scare the living crap out of everybody."

Queen was struck, too, by their friendship. When his mother dies, nobody in the ATF does a thing (and Queen uses the book to settle some scores with his supervisors, whom he considers gutless bureaucrats), but when his fellow Mongols hear of his loss, "they hug me. They tell me they love me. They were there."

"As time went by," Jarvis says, "Billy really got into the lifestyle."

Yet Queen says that if he had to do it all over again -- become a Mongol -- he would pass. His undercover investigation forced his ex-wife to relocate with his two young sons, who didn't understand why he was gone so long and looked so weird. The prosecutions were satisfying, Queen says. But most of the Mongols are out of prison and back on the street. And because of the book and the prospect of becoming movie stars, "they're bigger than ever," he says. "This thing has been like a recruitment tool."

Former ATF agent William Queen spent two years under cover as a member of the Mongols, an outlaw motorcycle gang.

William Queen, left, with a Mongol identified in "Under and Alone" as Easy. Mel Gibson's production company is turning Queen's undercover experiences with the bikers into a movie.