A Pact (2013)

A dark psychological thriller, A Pact tells the twisted story of a contentious love triangle. As teenagers, Paul tricked Georg into handing over his girlfriend Anna to him. Georg agrees, on the condition that he can have her back whenever he wishes. After decades of silence, when Anna and Paul have a family together, Georg suddenly re-appears. Strange things start happening to Paul, and it soon becomes clear that Georg has not forgotten the pact.