A young man wakes up in a strange room, with no memory of who he is or how he got there. He quickly learns that he's now under the control of the brutal criminal gang, Inferno, and they've given him a new name -- Zwei -- and set him up with their most talented assassin, a mysterious woman named Ein. Zwei has no choice but to become an Inferno agent, and Ein's first lesson is simple: only the strongest survive, and sometimes that means killing others in order to stay alive.