This is indubitably a well-acted, tightly-directed and hugely enjoyable movie - right up to the last five minutes. Then, really oddly, it seems as if the writer choked over his word processor and the film had to be ended in such a way as to leave viewers entirely mystified, with no prospect of resolution. The entire notion of enforced claustrophobia on human beings, in order to test their psychological and physical limits is not exactly an untrodden path - but to seduce the viewer into complete complicity with the writer and actors, and then to leave them hanging, at the conclusion, by an inexplicable thread, is not just annoying. It's a bit silly.
The movie still grips like superglue and is beautifully put together. But oh - the disappointing ending.....
** (two stars out of five)