Starring Emily Perkins. Rated 18A.

There is nothing quite like the dread anticipation of sitting through the sequel to a crappy movie. Canadian director John Fawcett's 2000 teen horror flick Ginger Snaps--with its ridiculous plot, low-budget gratuitous gore, failed attempts at dark humour, and ill-executed feminist message--is almost impossible to watch. Amazingly, the sequel, Ginger Snaps II: Unleashed, is a witty, gripping thriller.

The first film centred on two codependent goth sisters Brigitte (Emily Perkins) and Ginger (Katharine Isabelle), who are alienated from their suburban peers and freakishly obsessed with death. As they mope around a local park one night discussing Ginger's first menstruation, a mysterious creature attacks her. Over the next few weeks, Ginger gradually transforms into a werewolf--complete with excessive body hair, an insatiable sexual appetite, and a creepy little tail--and the overly earnest Brigitte spends the remainder of the film trying to discourage her from annihilating their high school's in-crowd. By the time the full moon rolls around, Ginger has morphed into a deranged she-wolf and Brigitte is forced to murder her--but not before she is infected with her sibling's blood.

Ginger Snaps II: Unleashed, which hands over the directorial reins to fellow Canuck Brett Sullivan (who edited the first flick), sees Brigitte on the run. She is hunted by a new werewolf and is shooting up monkshood daily to fend off the effects of the wolf virus. Brigitte accidentally lands in rehab, where the drug that she desperately needs is out of reach. Her sole ally is a preteen outcast named Ghost.

Unlike its predecessor, this gore fest manages both sophisticated humour and a more subtle feminist line. (In one scene, Brigitte tells a pushy group-therapy leader that she fantasizes about gorging on the guts of her fellow junkies, and the leader writes "lesbian?" in her notebook.) The treatment facility is shockingly inhumane; the young female patients are treated like prisoners, and horny, frat boy ­ish male nurse Tyler (Eric Johnson) routinely coerces his teen trusts into sexual acts. Perkins's outstanding performance renders this merging of social commentary with horror convention plausible and effective.

On the whole, the film is surprisingly gripping. Then again, Ginger Snaps isn't exactly a tough act to follow.