The crew of a Spanish TV reality show, accompanying Barcelona firemen on a routine call to an apartment block, records the sudden outbreak of a rabid virus in this well-sustained and often terrifying shocker. With the exits sealed off, they continue taping the unfolding pseudo-zombie nightmare in a frenetic, shaky-cam style, complete with creepy night-vision footage, startling jumps and out-of-focus menace. Matter-of-fact performances and the absence of soundtrack music add extra realism, before a breathtaking swerve into unexpected territory. Writer/directors Jaume Balagueró and Paco Plaza pool their wayward cult horror talents to work the Blair Witch faux documentary aesthetic - with added 28 Days Later-style rage victims - to urgent perfection.

A television reporter and cameraman follow emergency workers into a dark apartment building and are quickly locked inside with something terrifying.