If you've ever spent much time in a hospital, you might recognize the characters in "Nurse Jackie," the latest Showtime series to thrive on realistic, recognizable characters.

Edie Falco ("The Sopranos") stars as Jackie, a longtime nurse who doesn't suffer fools gladly but is equipped with an empathetic nature for patients in their most desperate hours.

Don't mistake that for a warm and cuddly persona. When new nurse Zoey (Merritt Wever, a wonderful scene-stealer) arrives at New York's All Saints Hospital, Jackie quickly sees a need to set ground rules for her.

"I don't do chatty. I like quiet," Jackie instructs in clipped tones. "Quiet and mean. Those are my people."

Yes, she can be a gruff mama lion on the outside, but Jackie is the first to berate herself, agonizing when a doctor's mistake leads to a patient's death. She inevitably wonders, could I have done more?

Jackie is a complicated character who makes choices that aren't easily understood, at least not early in the series' 12-episode run, which begins tonight at 10:30 following the season premiere of "Weeds."

Like the title character on "House," she's addicted to pain killers (for a bad back) and regularly has sex with the hospital pharmacist. Does she truly have feelings for him or is she just trading sex for pills? And how does this unhealthy relationship conflict with her life off the job?

Executive producers/writers Liz Brixius and Linda Wallem surround Jackie with a phalanx of characters who quickly become as fleshed-out and as real as Jackie, from amusingly awkward Nurse Zoey to frat boy Dr. Fitch "Coop" Cooper (Peter Facinelli). Anna Deavere Smith ("The West Wing") does a severe turn as by-the-book ER administrator Gloria Akalitus, a former nurse who's hardened as she's advanced in her career.

The relationship between Jackie and British Dr. Eleanor O'Hara (Eve Best) may remind viewers of the Carrie-Samantha dynamic from "Sex and the City," particularly when they lunch at posh restaurants where the doctor picks up the tab. (Executive producer John Melfi is a "Sex and the City" veteran).

But largely the show is unglamorous -- more "ER" than "Grey's Anatomy" -- and not all that immediately concerned with the love lives of its characters, which distinguishes it from both of those popular TV medical dramas.

Tonight's pilot suffers from a few up-the-ante, "look-at-me!" moments, like when Coop grabs Jackie's breast and claims it's a nervous tic. Future episodes are more grounded and less desperate to shock for the sake of grabbing viewer (and network) attention, but they're no less enthralling with both drama and humor.

When a polite couple arrives in the ER, Jackie guesses they're from the Midwest. How did she know? "Because you're in pain and you're apologizing," she acutely observes.

In addition to the realism of the characters, the look of the show is striking, particularly the All Saints set. Portions of it look high-gloss modern, but then you turn a corner and it's dark with walls made of stone, presumably representing the original hospital that's been added onto over time.

Falco's performance sets the bar high for everyone around her. With her short, chopped hair and tough-love approach to training the newest nurse ("The doctors are here to diagnose, not heal. We're the healers."), Falco makes Jackie an enjoyable character to spend time with -- even when she makes bad choices.

No wonder Showtime opted not to pick up any new pilots from their recent batch of development. Network executives could probably see the gem they have in "Nurse Jackie," an early high point in the summer TV doldrums.