Catherine Bell's first appearance on JAG should have been her last. In 1996 she had a three-line walk-on as Lt. Dianne Schonke, the long-lost girlfriend of Lt. Cmdr. Harmon "Harm" Rabb (David James Elliott), the show's hero. In her very next scene, poor Diane was a bloodied corpse, the victim of a stalker. Yet 10 months later, Bell was back–as Elliott's costar.

How to explain her return from the dead? Call it chutzpah. Hearing that JAG was seeking to cast a new sidekick for Harm–Maj. Sarah "Mac" MacKenzie–"I wrote this letter [to executive producer Donald P. Bellisario]," says Bell, 30, "that said, 'I'm right for the part. I want to work with you again. I want to be Mac' I remember dropping it in the mail, going, 'Oh, God, I hope this works.'"

It did. In the summer of 1996, Bellisario was scrambling to revive JAG, which NBC had just canceled due to low ratings. CBS adopted the series and ordered 13 new episodes to begin in January '97. Reading Bell's letter, Bellisario remembered her as "a good actress with a very pretty laugh," he says. "I thought, 'How can we use her twice?' Then I thought, 'What if we play off the fact that she looked just like the love of Harm's life?'"

So Bell was cast as Mac, a Marine Corps lawyer and Harm's feisty fellow investigator for JAG–the Judge Advocate General's office–as well as a dead ringer for his (also dead) girlfriend. Not surprisingly, the pair clicked immediately. And though they're still as platonic as Scully and Mulder on The X-Files, the sexual tension–combined with topical scripts–has helped JAG soar into Nielsen's Top 20.

Elliott credits his costar for much of the series' success. "She brought sparkle to the show," he says. "She's not moody, and she's very up most of the time." And when she's not? Elliott laughs. "We had this running scene. She hates running, and we had to run all day. She was flagging, and I rubbed her nose in it."

That doesn't happen too often. Bell took up kickboxing eight years ago and often displays her skills on the show. Also handy with a rifle ("I've always known about guns. I used to go to shooting ranges"), she can fieldstrip an M-16. Like real Marines (who regularly send her fan letters), "she perseveres and is tough," says her actor-husband, Adam Beason, 29.

Pushing the envelope is nothing new for Bell. Born in London to Peter, an architect, and Mina, an Iranian-born nurse (now Bell's personal assistant), she was just 2 when her parents divorced, and she and her mother moved in with Mina's parents in L.A. (Her father died three years later in a car accident.) At age 7, spotted at a local McDonald's by a pair of casting agents, Bell was hired for a Baskin-Robbins ice cream commercial. Though other TV ads soon followed, her real ambition was to become a doctor. In 1986 she enrolled as a premed student at UCLA but dropped out in her sophomore year to give modeling a try.

Then 19, Bell spent four months walking the runways in Japan and hated it. Lonely and homesick, she gorged on fast food and gained 20 pounds. "Shakey's [Pizza] had this great DOLLAR]8 all-you-can-eat buffet," she says. "I would do that and gain even more weight. I came home [to L.A.] so depressed and fat." But, determined to be an actress, she slimmed down and signed up for classes.

Roles slowly began coming her way with guest shots on Hercules, Dream On and Friends. It was on the set of the 1992 black-comedy movie Death Becomes Her (in which Bell was Isabella Rossellini's body double) that she met Beason, then a production assistant. They tied the knot on May 8, 1994–the second anniversary of their first date.

The couple now share a three-story, contemporary-style house in Sherman Oaks, Calif. "I have all this fun stuff that I love to do," says Bell–ticking off snowboarding, motocross-racing and waterskiing–but unfortunately no time to do it, thanks to her 15-hour days on JAG. On weekends she and Beason hang out with their Italian greyhounds Zoe and Leo.

She also dreams of life after JAG. "I want to do features," she says. "My favorite movies are action movies, but there are so few strong women characters. That's got to change." Maybe she should write a letter.

Michael A. Lipton
Irene Zutell in Los Angeles