IN PLAIN SIGHT. 10 p.m. Sunday, USA.

THERE ARE no doubt women in law enforcement who play by the rules, keep their private and professional lives separate and manage to get along with bosses and colleagues who aren't even slightly afraid of them.

I hope they're not expecting to get their own cable shows.

Starting Sunday, Kyra Sedgwick's steel magnolia in TNT's "The Closer" and Holly Hunter's wounded wild child in TNT's "Saving Grace" have a sister under the skin in Mary McCormack, who's playing U.S. Marshal Mary Shannon in USA's "In Plain Sight."

As one of the officers charged with making sure people in the federal witness-protection program don't spoil its record by getting themselves killed, Mary would seem to have a job compelling enough, at least, for broadcast television, where shows like CBS' "Without a Trace" - and, all right, just about everything on CBS - showcase men and women whose jobs are the most interesting thing about them.

USA, whose shows tend to strive for the middle ground between broadcast procedurals and the edgier dramas of FX (and lately, AMC), is as usual looking to have it both ways in "In Plain Sight."

The witness-protection program, or WITSEC, as it's generally referred to here, does drive the main stories in the show, whose extended, 76-minute premiere involves an investigation into the death of the son of a mobster whose family's in the program.

Every episode yields some new detail about what might or might not be expected to happen when people leave their old lives behind and put their lives in the hands of others. So there's plenty to work with there.

But there's something, or several things, about Mary that just won't let her take a back seat to whatever drama's going on around her.

She's cranky, for one thing. Cranky about parking tickets, visiting sisters, birthdays, recalcitrant witnesses and many of the regulations that govern the U.S. Marshals Service.

Her boss (Paul Ben-Victor) really does seem afraid of her.

She also has a hot boyfriend (Cristián de la Fuente, of "Dancing with the Stars" fame) and a long-suffering partner (Frederick Weller) whose first name is, confusingly enough, Marshall).

Stationed in Albuquerque, N.M., Mary appears to be the sole support of her not-so-aged mother (Lesley Ann Warren), and while Mom's ditziness alone could explain the daughter's crankiness, it doesn't. Not quite.

"What's the deal with babies?" she asks at one point in next week's episode while watching others fawn over one. "I don't get them."

McCormack, a rangy actress who looks more comfortable in Mary Shannon's tank tops and casual jackets than she ever did in the lawyerly business suits she wore way back on "Murder One," manages to make all this crankiness intermittently endearing.

It doesn't hurt that she's as fiercely protective of her charges as she is just plain fierce, or that most of the people around her, including her fraidy-cat boss, seem to love her, even when she's screaming at them.

In an episode scheduled for June 22 featuring a memorable guest-star turn by comedian Dave Foley, we get a look at just how far Mary's willing to go, both for those she loves and those she's sworn to protect.

Still, in the four episodes I've seen so far, I've yet to figure out exactly what's irking Mary.

Whatever it is, it's not exactly hiding in plain sight. *

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