Coherence (James Ward Byrkit, 2013)

A bland dinner party of friends turns into an existential nightmare in an impressive zero-budget debut by the director. But who needs a budget when you have a brain, and although the notion of a bunch of people becoming trapped in a confusion of realities, which occurs here as a comet passes close to Earth, is now becoming another sub-genre in itself - partly owing a debt to films such as Nacho Vigalondo's Timecrimes and now continued by the films of Mexico's Isaac Ezban, for example - the twists here are both unexpected and deeply disturbing, even if it does giddily overreach itself and turns into quite a muddle in the process.
It's a very difficult film to categorise; a summary of the premise would suggest science fiction, but it's really a drama that turns into horror without violence. And to say anything more would be a cruel spoiler.

6/10