As a New York-based talk-show host whose cozy world is shattered when a gang of thugs cracks her skull and murders her fiancé (Naveen Andrews) during an evening stroll in Central Park, her performance is effectively nuanced, a subtle but convincing mix of impotent terror, vengeful rage and, ultimately, remorse. It would represent a star-making turn for an actress with a lesser résumé; for Foster, it is merely a platform to show off her dramatic range.

The only problem is the movie itself. There is little wrong with The Brave One, really, save for the fact that it bills itself as something it is not. Jordan and Foster would have us believe that this is high-minded examination of American violence, and the ways even a single brush with it can transform an otherwise peaceful, law-abiding citizen into a rogue killer.

Foster makes the transition believable, and it is hard not to sympathize with Erica, the happy-go-lucky city-dweller who is robbed of her security and, in desperation, buys a gun. Once she musters the courage to leave her apartment, she finds herself immersed in a culture overrun with thieves, murderers and rapists. Take a look around, the movie seems to be saying, and you’ll find them – they’re everywhere, you’ll see!

In fact, Erica seems to be going out of her way to find them, with a little help from her unwitting accomplice, Detective Mercer (Terrence Howard). The problem is that as much as one can empathize with her righteous rage – and judging from the wild cheers it elicited at a recent screening, her subsequent killing spree – it is almost impossible not to view her as a public menace, conflicted though she may be. The Brave One is Death Wish in sheep’s clothing, with Foster playing Charles Bronson’s vigilante with a touch of 21st-century sensitivity.

Is that a bad thing? Not necessarily, but Death Wish was not serious entertainment, and neither is The Brave One. It is a lurid, finely crafted thriller, entertaining to the last, but to present it as a solemn meditation on the nature of violence is intellectually dishonest. As a tense crime drama, invigorated by Foster’s virtuoso performance, it works. Moralists, however, should be dismayed by its casual glorification of vigilante justice and its suggestion that female empowerment is as simple as packing heat.

Note: Foster recently decried the violent state of American film, citing Sin City – a bloody comic-book fantasy in which a young girl is abandoned and nearly raped – as symptomatic of the problem. If Ms. Foster, who plays a terrorized mother in Panic Room and an all-too-eager killer here, wishes to mop the blood off theater floors, she might start by choosing her own roles more carefully.