Agathe von Trapp, the eldest daughter of a well-known musical family, overcomes many obstacles to pursue her musical career and move to the United States.

At a climate research station in the Alps, the scientists are stunned as the nearby melting glacier is leaking a red liquid. It quickly turns to be very special juice — with unexpected genetic effects on the local wildlife.

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.