This is one of those great little ideas every writer dreams of, that moment you latch onto a very simple, very cheap way of making something with a fresh concept you can wring drama out of. With Exam, writer/director Stuart Hazeldine pretty much succeeds on those levels - this is a smart British movie that plays like it came from the stage; one setting, a small cast (of largely unknowns) and a controlled idea bursting with imagination and coated with a discrete sense of mystery.

The setting is almost a character in itself, posing numerous questions - where are we? Inside some corporate megastructure? Is this the future? If so, how far away? None of these have answers in the movie, you're left to guess - as indeed you even are about the characters; neatly defined as per their creed (White, Black, Brown), they have no names and that's where Hazeldine takes a risk - they need to stand out strongly enough as archetypes to survive not having too much backstory unfold across the running time (which, sweetly, plays out in real-time). They mostly do, even if the acting sometimes lets the side down - Luke Mably far too stock as a bolshy candidate, for instance, whereas Jimi Mistry (outside Colin Salmon the only one you'll recognise) nicely amps up a layer of dark ruthlessness about his character. All though are representing different things, and that's what Hazeldine's ambitious script plays with - his direction too keeping proceedings reined in, nothing flashy, simply psychologically deconstructing each of these people as they try to figure out how to pass the titular exam.

It lets itself down by the climax, unfortunately, when Hazeldine isn't brave enough to go for the jugular - revealing something of a fake out, not to mention doling out a shade too much information that dampens the mystery; plus I also called the true identity of one of the players very early on, and so will you if you're paying attention. Nonetheless, for a good 80 or so minutes, Exam is a tense, claustrophobic look into the human mind that deserves not to be missed.