When Benjamin Bratt was a kid, he spent his weekends at San Francisco's most exclusive address: a waterfront property with 336 rooms and a breathtaking view of the Bay—scenic Alcatraz Island. Yes, that Alcatraz Island.

The future Law and Order star, then just 5 years old, was only dimly aware of the civil-rights protest that had brought him and his four siblings to the wind-swept ruins of the country's most notorious prison (his mother, a Peruvian Indian, had joined the American Indian Movement's 19-month-long occupation of the island). "For a kid, Alcatraz is the ultimate playground," says Bratt, who spent his non-Rock years in San Francisco's Glen Park neighborhood. "My brother and I would hook up with the other kids and explore the industrial side of the island, walk on the conveyor belts, turn over boulders and find little crabs."

This youthful detective work may have paved the way for the 33-year-old actor's current assignment. He's the newest cop on NBC's Law and Order, the enduring crime drama that seems to thrive on the periodic shake-ups of its cast list. As Detective Reynaldo ("Rey") Curtis, Bratt is a study in contradictions: a straight-laced, politically conservative Latino husband and father who, in the course of two TV seasons, has strayed into an affair and excelled at his job. "Curtis can be kind of a hothead," says Bratt. "I'm not like that at all. I'm loose."

Bratt wasn't always so relaxed. His parents divorced when he was 4 years old, and he has never had a close relationship with his father, a sheet-metal worker of German and English descent. Bratt's mother, a nurse who left her native Lima as a teen-ager, had to go on welfare to care for her children. "It was hard on her," says Bratt. "She pretty much raised us single-handedly."

Movies—anything starring Bruce Lee or Kurt Russell—provided an escape, but Bratt didn't think about acting until he enrolled at the University of California at Santa Barbara, where he majored in theater. After graduation, he earned a spot at San Francisco's prestigious American Conservatory Theater school, but his days as a struggling drama student were numbered. "I was totally broke and sharing a place with my brother," he says. "Four days later, I had my own series."

Bratt's big break was the lead role on Juarez, a failed ABC pilot about a young Mexican-American lawman that ended up airing as a TV movie in 1988. After that disappointment, Bratt landed a starring role on NBC's short-lived Nasty Boys, a flashy crime drama about drug-fighting ninja cops that led to a friendship with the show's executive producer, Dick Wolf, who also helms Law and Order. "Ben is extraordinary looking, like some Peruvian god," says Wolf. "The volume of mail we got about him for Nasty Boys was astounding. And he's a good actor, which doesn't come along that often."

Although Wolf offered Bratt a few guest spots over the years, the actor declined, preferring to take supporting roles in films like Clear and Present Danger and The River Wild ("I've played so many cops," Bratt says, "I'm like the brown Brian Dennehy"). But in 1995, Wolf offered Bratt a shot at joining the Law and Order cast full time. Actor Chris Noth, whom Bratt replaced, had been "immensely popular," Wolf says, but Noth's character was written out of the show because his relationship with his partner was becoming so amiable that "they were practically finishing each other's sentences."

Bratt's good fortune and his subsequent move from L.A. came at a price, however. A six-year relationship with his girlfriend, a documentary filmmaker, ended earlier this year. (Bratt lives alone in Manhattan's fashionable Chelsea neighborhood.)

After two seasons on Law and Order, Bratt has begun to feel at home. "I get recognized now, and it's always in a complementary way," he says. "It's been a gift. With strings attached, however: Law and Order's hectic nine-month-long shooting schedule prevents Bratt from taking movie roles, except during his summer break. His most recent film, Follow Me Home, a revisionist western directed by his older brother Peter, was shot before he joined Law and Order and is only now being seen, in a limited release. To win his role as an ex-convict turned street artist, the actor had to prove that he wasn't, as his brother said, "too pretty" for the part. So Bratt shaved I head, grew a ragged beard, covered himself in fake tattoos and wore stained, broken prosthetic teeth. The transformation worked. At first, even Bratt's family didn't recognize him. "Laurence Olivier said he couldn't get into character until he walked in their shoes," says Bratt. "And I say I can't get into character until I've worn their teeth."