Rammbock: Berlin Undead (2010)

Just when Michael arrives in Berlin to visit his ex-girlfriend Gabi, a terrible virus starts spreading across the city at a rapid pace, turning people into mindless homicidal maniacs. Much to Michael's concern, Gabi's not home; instead, he meets Harper, a teenage plumber's apprentice at work in her apartment block. Together, they manage to barricade themselves when raging hordes of infected people swarm the building. Surrounded by these thirsty zombies, Michael and Harper have their hands full to survive - and it will take all of their ingenuity to make their way out to try and find Gabi.