After playing Faith, ''Buffy the Vampire Slayer'''s darkly wired, serially sexual huntress, any role might seem staid. Still, it's troubling to watch Eliza Dushku in Tru Calling -- her first starring gig -- bound in a lab coat, slightly glum, forced to say lines like ''Trust that I know what I'm doing. Or maybe I don't. I don't know.''
Someone doesn't know what they're doing, because Fox is squandering ''Tru'''s gift of a premise. Dushku plays Tru Davies, a night-shifter in the morgue of a shamefully nondescript city who discovers a power: Incoming corpses ask for her aid, and ZIIING!, she time-travels back to the morning so she can prevent their deaths.
Why her? Maybe because as a child she saw her mom murdered. Or maybe because she's so damn hot! If as much attention were paid to the scripts as to the oiling, painting, and glossing of Dushku's pouty lips, we'd have a funky cross of ''CSI,'' ''The Sixth Sense,'' and ''Groundhog Day.''
But such is not the case. The relationship between viewers and any fantasy show is delicate: We suspend our disbelief, you don't take advantage. ''Tru'' cheats with flamboyance. Each episode boasts at least one ludicrously convenient plot point: If you're a med student conducting heinous, secret experiments, wouldn't you lock the door? And if you didn't, and some strange (but hot) girl barged in and threatened you, wouldn't you lock the door the next time? Meanwhile, Dushku's Tru, who should anchor this otherworld, switches personalities like days-of-the-week undies, but without the whimsy. Is she an uptight good girl or a jaded badass? Either way, she's a bore. A hot, pouty bore.
Morbid ratings aside, Fox has picked up ''Tru'' for the full season and some smart tinkering is under way: While her boss (Zach Galifianakis), the only one who understands Tru's calling, is developing into a sweet, dorky mentor, Tru's testy sister (Jessica Collins) -- one of those ''ambitious'' women TV loves to hate -- hardly appears anymore. That leaves more time for Tru's rascal kid brother, played with slouchy ease by Shawn Reaves, who's the best thing on the show. The Dec. 18 episode, in which Tru may have murdered an ex-beau, was good, soapy fun -- despite some pesky logic problems (and a butcher knife so laboriously reintroduced, it was almost its own character). Most intriguingly, Jason Priestley joins ''Tru'' in March for a guest stint as a mysterious forensics guy. He has to provide more spark than Tru's latest love, Luc (Matthew Bomer), who gazes at her with the ice blue eyes of an adoring, neutered husky. Dushku needs someone to riff with, not roll over.
In short, Dushku has to regain the vibrancy she buzzed with in ''Buffy'' and ''Bring It On,'' and the writers can help. Liven Tru up. Give her a sense of mischief. Or humor. Faith would agree -- any girl who consorts with the dead needs spirit.