When teenager Liz (Birch) staggers through the deserted corridors of an English boarding school to raise the alarm, the investigation is about to begin. She's the sole survivor of the four classmates who've been missing for two weeks, trapped inside a disused army bunker unbeknown to anyone. Under the sensitive promptings of a police psychologist (Davidtz), she's about to reveal the truth about what really happened in 'the hole', and why her classmates - cool dude Mike (Harrington), rugger bugger Geoff (Fox) and It-girl wannabe Frankie (Knightley) - didn't make it. Her story of an adolescent crush gone wrong points the finger at geeky resident fixer Martin (Brocklebank), yet under subsequent questioning his entirely different version of events is equally plausible. This British teen thriller, part-funded by the Film Council, comes on confidently. Clint Mansell's electro score creates a genuine sense of anticipation, while screenwriters Ben Court and Caroline Ip (working from Guy Burt's novel After the Hole) adeptly set up the central conundrum, which Birch's able performance subtly sustains. Is Liz sinned against or psycho? The trouble is, Nick Hamm's film, for all its intriguing ambiguity, does eventually have to make its mind up, at which point it swiftly starts to fall apart, blowing its hard-earned credibility with showy directorial button-pushing.