German-American Paul Schumann is a brilliant mobster hitman who gets caught and is offered a deal: hunt down and kill Reinhardt Ernst, the ruthless architect of Hitler's clandestine rearmament or face the electric chair. From a boarding house near the Tiergarten, a huge park in central Berlin also known as the Garden of Beasts, Schumann stalks Ernst while a Berlin police officer and the entire Third Reich apparatus search frantically for him.