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
