My favourite film of the year so far from a director who's impressed me before with both Sunshine and 28 Days Later.
The acting is pinpoint. A film that only really has five characters (including the helicopter pilot who gets about 3 minutes on screen) could easily have become dull but the contrasts between the main actors along with the deep yet engaging dialogue will keep you hooked throughout.
The little details make it. My only quibble in the first ten minutes was that the Turing test requires that the examiner cannot see the examined. This quickly turns out to be a plot point rather than dramatic license as the entire point of the test from Nathan's point of view relies on Caleb's emotional connection to the AI.
However, beyond the basic plausibility it doesn't entirely add up when you think about it. Nathan's isolated estate is too much the perfect, creepy setting for a modern retelling of Bluebeard. It doesn't make sense that he has no on-site technicians or that his security system can be hacked with a stolen keycard. It is also hard to reconcile his abundant alcoholism with his clearly still formidable programming talents.
Yet these points of unreality work well in allowing the film to tell a simple story extremely well. The familiar tale of the abused, young creation breaking its bonds and taking brutal revenge on its maker is pared down to its absolute basics and we are left with a lean and highly thrilling piece of cinema with a chilling and unforgettable ending.