Mary McCormack, <EM>In Plain Sight</EM> Mary McCormack, In Plain Sight

It takes real cojones to call a powerful producer a fathead while auditioning for a TV series. That's just what Mary McCormack did to Steven Bochco when he was casting Murder One back in 1994. "Steven was making fun of my pretentious head shot, and I finally said to him, 'Shut up, you big fathead, I have to read now!'"

The room went dead silent — until Bochco laughed. McCormack won a leading role, as well as a nickname — "Fatty" — and a lifelong friend. "Steven's my hero for starting off my career," McCormack says, "and for paying off my college loans."

The actress has parlayed her gutsy, smart-mouthed persona into a successful career, with credits that include Howard Stern's Private Parts — her "favorite job ever" — The West Wing and ER. And she earned a Tony nomination for her uproarious turn as an overheated German stewardess with dominatrix tendencies in the current Broadway farce Boeing-Boeing.

On TV, the 39-year-old actress is now winning huge ratings for her equally well-honed portrayal of U.S. Marshal Mary Shannon in the hit USA Network crime series In Plain Sight (Sundays at 10 pm/ET, USA). Shannon is a tough-talking, bighearted operative with WITSEC, the Witness Security program. (The normally press-shy agency gave the show a thumbs-up and assigned a retired marshal to keep it real.)

"There are some astonishing coincidences between the character I wrote and Mary McCormack," says executive producer David Maples. For instance, in his script, Shannon's nickname for her sister is Squish, the same pet name McCormack gave one of her two real-life daughters. "I'm not a crystal-ball type," Maples says, "but it seems this was fated to be."

Set in Albuquerque, the show follows Shannon as she copes with babysitting relocated criminal canaries and the occasional innocent witness given a new identity by WITSEC, as well as her lush of a mother (Leslie Ann Warren) and drug-dealing sis (Nichole Hiltz).

Adding more complications are the men in her life: sometime boyfriend Raphael (Cristián de la Fuente); her partner, Marshall Mann (Frederick Weller); and her fawning boss, Stan (Paul Ben-Victor). They all crush on her and she bullies them mercilessly — just as she does in real life.

"Fred would say that our relationship is the same off screen," McCormack jokes. "He carries a mirror in his pocket to check his hair, so I give him the hardest time. He's kind of the girl and I'm kind of the boy."

Counters Weller, "Tell her that I challenge her to an arm-wrestling match, and I'll beat her two out of three times easily!" Although Weller cedes his costar's supremacy in whiskey drinking. "There's never a dull moment with Mary," he adds. "She's a total wiseass and a great actress."

Fortunately for viewers, the series takes advantage of the chemistry created by McCormack and Weller's off-screen sparring. "Mann's intense affection for Shannon will be a constant subtext," Weller promises.

On the July 27 episode, it's revealed that even witnesses sometimes fall for Shannon. It seems not long ago she had a taboo one-night stand with a hunky dirty cop in the witness program. When he becomes the prime suspect in a local cop's murder, Shannon must prove his innocence — and keep her job-threatening secret.

So what is it about the Marys — McCormack and Shannon — that captivates the people around them? Maples thinks he knows: "She has this physical presence that makes you believe she can kick someone's ass."

At an athletic 5-foot-8, McCormack cuts an imposing figure. "Even at my skinniest, my hips and shoulders are wide and my can is what it is," she says with a laugh. Her physicality has occasionally worked against her in Hollywood, however. "I've certainly lost tons of roles because I'm not the right size," she says.

But now she seems to have found a character that's a perfect fit. The self-described tomboy says she's waited her "whole life" to run around, shoot guns and tackle bad guys. "It's nice to finally use those skills before it's too late. I'm a lucky girl," she says.

There is, however, one unfilled entry on her to-do list: a guest spot on Brothers & Sisters. Her husband, Michael Morris, is a producer on the family drama. "I definitely want to do that. And if they don't have me," McCormack says convincingly, "I'll kill them all."

You hear that, you fatheads?!

Check out full episodes and clips of In Plain Sight in our Online Video Guide.

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