Just before midnight, the rented truck, its headlights dimmed to avoid detection, pulled up in front of the darkened house in Rockville. Within seconds, the tiny band of commandos was out of the van and dismantling a section of chain-link face. Furtively, they entered the basement.

In less than an hour they had loaded their precious cargo and were barreling south on I-270. Seventeen monkeys were on their way to "freedom" in South Carolina with a band of benefactors who believed that for monkeys, at least, there is no justice in Maryland.

Five days later, at a second stop in Florida, the situation changed for this ragtag band of animal advocates bent on saving the monkeys from lives at a Silver Spring research lab. By now the monkeys' fate was being debated in coast-to-coast calls by a network of worried animal lovers. The decision was made, and word came from Maryland: "Come on home. That's the best deal for the monkeys."

The sometimes slapstick drama of Montgomery's monkeys had become the rallying point for the animal welfare movement in America, a formidable lobby with millions of members who believe that animals are among society's most exploited and least understood victims.

The disappearance of the monkeys from the Rockville basement where they were in custody was probably the zenith of the controversy begun by an unprecedented raid on the Institute for Behavioral Research. The new twists to the case, however, show no signs of abating.

On Friday at 10:15 a.m., one of the monkeys died of cardiac arrest after being attacked by another monkey. The day before the National Institutes of Health, which had funded the research in which the monkeys were being used, suspended its $200,000 grant to the laboratory, a suspension that is unprecedented in scientific circles.

It began months ago when an unlikely undercover agent from the People for the Ethical Treatment of Animals infiltrated the lab. Since then the monkey case has attracted the fervent support of such celebrities as writer Cleveland Amory, chairman of the Fund for Animals, and Christine Stevens, wife of Kennedy Center chairman Roger Stevens, and a movement with enough factions, ideologies and feuds to satisfy a political scientist.

It is a movement of philosophers and celebrities, radicals and conservatives, the mild and the wild. It is big enough to embrace the ideas of People for the Ethical Treatment of Animals, with its penchant for guerrilla tactics, and of Stevens' Animal Welfare Institute, with its clout on Capitol Hill. It is also small enough for some emotional clashes.

"I've always said the reason the animals are crying in this country is the divisiveness in the humane movement," said actress Gretchen Wyler, vice chairman of Amory's Fund for Animals.

For all of these sometimes divided groups, the case of the Montgomery monkeys has been a watershed development.

"This is the single, most forward step ever taken for these lab animals," said Wyler. "A landmark case," said Amory, of the upcoming court battle to decide the monkeys' fate.

It is a landmark, too, for the giant research community, which sees the case as a threat to its most valuable tool in advancing science -- the research animal. It is a well-timed assault, the scientists say, carried out by zealots and calculated to color congressional hearings Oct. 13 and 14 on the use of animals in the laboratory.

The events that led to the now national controversy were set in motion last May when a college student named Alex Pacheco ran his finger down a list of labs registered with the United States Department of Agriculture and stopped at the entry, Institute for Behavioral Research, 9162 Brookville Rd. "It was the one closest to our office," Pacheco says nonchalantly, of the lab's location near his group's Takoma Park home.

To help him in his work for animals, Pacheco decided to apply for a job at the lab and learn firsthand about the way research animals are used. A few years before, the 23-year-old George Washington University student had undergone the transformation from animal lover to animal advocate when he visited a slaughterhouse near Montreal. Pacheco had been horrified. He read Animal Liberation, the book that is the bible of the radical animal rights movement. Then he stopped eating meat and started "doing what's best for the animals." He saw laboratory animals as the orphans of the movement, the creatures always ignored in the public relations pushes to save the whales or the dolphins or the baby seals.

But Edward Taub, the chief researcher at the institute, knew none of that when he hired Pacheco. To Taub, he was just a college student interested in animal behavior and a part-time job. The researcher now ruefully recalls, "I came home and told my wife, 'I have a marvelous student. I told him there was no position, but he volunteered to work out of pure interest.' "

During the week of May 11, Pacheco was ushered for the first time into the institute's now celebrated monkey colony. "I couldn't believe it when I walked in and saw all these little Chi-Chis," said Pacheco, who once had a pet monkey by that name. But within days he said he saw other things that made him wince.

Pacheco started snapping pictures, at first sneaking his Canon 35mm camera into the lab in the pocket of his jeans, and later using his organization's last $160 to buy a tiny Olympus XA.

"I was going to do an expose and embarrass the hell out of them," Pacheco says he first believed. But as Pacheco's anger grew, so did the vision of his mission.

Running out of money, Pacheco traveled to Manhattan July 13 to show his slides to Wyler in her apartment high over Central Park South. "I must tell you that after 12 years in the movement my tears don't flow much anymore, but I cried," Wyler confided recently.

The actress offered encouragement, and later more than $2,000 for legal fees. Amory, whom Pacheco visited the same day, handed him $500.

The crusade was on. Pacheco snapped pictures with a passion, and his paranoia grew. He borrowed an expensive walkie-talkie from the Fund for Animals. Now during late-night manuevers, a second operative sat outside IBR in a darkened car ready to relay a warning if an unexpected employe showed up. The Fund was giving Pacheco money and aid, but still he wouldn't tell them where the laboratory was. "Like the CIA, he worked on the need-to-know principle," said the Fund's Lewis Regenstein.

There were those in the movement who envisioned an Entebbe-style raid to free the monkeys. They would pattern their actions after those of the hooded figures who descend on labs and kennels in Europe to sweep the animals to safety. Known as the Animal Liberation Front, their exploits are chronicled by The Beast, a magazine in England, where their forays are said to be on the rise.

But that was not to be. Instead, Pacheco's group sought help from a local politician. His only advice was that the research lab was not exempt from Maryland animal cruelty laws, as the group originally had believed.

That cinched it, according to Pacheco. They would go to the police.

Pacheco gathered his final evidence during five late-night forays into the lab for clandestine tours with animal experts. Then he and two other animal advocates took their story to prosecutor Joseph Fitzpatrick and Sgt. Richard Swain.

Three days later, Montgomery County Police swept into IBR with a search and seizure warrant, taking away samples, documents and 17 soon-to-be celebrated monkeys.

Taub was shaving when he got word of the raid from an employe. Shocked and bewildered, he rushed to the institute, but it was not until two days later that the impact sunk in.

"I knew I ought to feel angry," Taub recalls, "but I realized I was feeling what a woman must feel when she's been raped. My career, all those years of work, my monkeys . . . they took all this while I had to stand by helplessly. It's everything that's important to me."

After the raid, the monkeys were placed in police custody in the Rockville home of Lori Lehner, another member of Pacheco's group. While the monkeys accustomed themselves to new, roomier cages built with $2,000 from the Animal Protection Institute and reportedly whiled away their time watching the television soaps, Taub fought mightily for their return.

The institute hired a partner from one of Washington's top law firms, Arnold & Porter, to handle the court battle. When it appeared the judge was ready to send them back to the lab, the monkeys disappeared. Taub insisted they had been "kidnaped," and in a press conference he appealed to the kidnapers "not to harm them in any way." A few days later, the monkeys were returned to their Rockville quarters, and only then, did word leak out that they had been in South Carolina and Florida.

Their exact whereabouts remained a closely guarded secret, as did the names of their benefactors-gone-awry.

Since the monkeys' return, Taub has been charged with 15 counts of animal cruelty. Police alleged that monkeys at the institute had unbandaged open wounds, were forced to live in filthy cages and at times go without food or water and that two had collapsed from this treatment.

Taub denied the charges, asserting that they were based on "distortions of the facts and total misunderstanding by an untrained young man of the research we have been doing." The 50-year-old physiological psychologist said he has dedicated his life to science and sees Pacheco's actions and the police raid as "an interference with the spirit of free inquiry."

Last weekend, the monkeys went back to the lab after the judge ordered their return pending further court action. On Friday, however, the judge reversed his decision, telling the county to find new quarters for the animals.

On Oct. 27, Taub will face trial on the misdemeanor cruelty charges in Montgomery County District Court, and the animal movement will be watching.

"I did not get involved in this for 17 monkeys," said Wyler, who plans to be right there in court. "With all due respect to those 17 monkeys, we are going for the bigger picture. Never in history has there been anything like this . . . . We are attacking the system, not the man. And Taub is fighting for the system's life."