IN THIS unlikely cross between Jaws and Carrie, fresh faced cheerleader for chastity Dawn (Jess Weixler) gets unexpected assistance in maintaining her purity when she discovers that she's cursed, or maybe blessed, with an unusual set of reproductive organs with a mind of their own plus a second lower set of choppers. Cue hormonal boys' shrieks of terror as she learns how to wrestle control of her own physicality from menacing men, including her malevolent step-brother Brad (John Hensley).

With many, many shots of caves, holes and hollows, you shouldn't expect subtlety in Mitchell Lichtenstein's feminist twist on vagina dentate. An appealing Weixler chews the scenery with élan but ultimately the story goes flaccid with repetitive gross-out scenes of penile decapitation and after almost 90 minutes the movie halts rather abruptly: the screenplay equivalent of coitus interruptus. Still, it's probably the date movie of the year, if you happen to be a parent.

The Escapist (15) ***

Prison movies, like prisons themselves, thrive on regimentation. So in The Escapist we have Brian Cox as the kindly old lag who will take Dominic Cooper, below left, under his wing, Joseph Fiennes as a lone rebel loner, Damian Lewis as Mr Big and Steven Mackintosh as Mr Big's predatory gay brother who enjoys the communal shower facilities. Yet what appears to be a straightforward gruff and grimy clinker about a prison break turns out to have more in common with Memento than The Shawshank Redemption, with an arresting expressionistic sound design, a jack-knifed plot and an existential twist.

The Ruins (18) **

"Four Americans on vacation don't just disappear," reasons one of the leads of The Ruins. Clearly they haven't been to the movies recently because attractive young American tourists routinely just disappear in movies such as Hostel, Turistas and Dark Water – although not without a bit of bloodshed and screaming first. This time it is college kids in Mexico, terrorised by a talking vine that also drinks blood. In a film that fumbles most of its attempts to build suspense or tension, one shot of the homicidal shrubbery's tendrils making off with a severed foot serves as a highlight.

Adulthood (15) **

Noel Clarke, left, directs and stars in this follow-up to Kidulthood, as a former street bully who is released from prison and finds that – surprise – it's not that easy stepping back into civilian life. It's an energetic variation on the genre, but the script and standard issue proposition that crime doesn't pay feel like something lifted out of CBBC.

• All on general release from Friday