Germany, 1945. Soldier Willi Herold, become a deserter of the German army, stumbles into a uniform of Nazi captain abandoned during the last and desperate weeks of the Third Reich. Newly emboldened by the allure of a suit that he has stolen only to stay warm, Willi discovers that many Germans will follow the leader, whoever he is.

When lovelorn Michael arrives in Berlin to return a set of keys to his ex-girlfriend, Gabi, as an excuse to see her again, he finds her apartment empty save for a couple of plumbers making repairs to the central heating. Just as Michael learns from the plumber’s apprentice, Harper, that Gabi has popped out for a while but will return soon, the apprentice is attacked by his boss who has unexpectedly and inexplicably transformed into a raging madman. Together, Michael and Harper manage to bundle the crazed plumber out of the apartment and barricade themselves safely inside. Within minutes, they find themselves trapped in apartment block under siege from a horde of similarly insane people, apparently hungry for human flesh.