Fleeing across a roof on a dark night in Victorian London, a thief crashes through a glass sklight to almost certain death. But an ambitious young doctor revives and reconstructs his shattered body, proudly showing off his handiwork at the Scientific Society. It is there that the robber picks up the key to a new existence, and on his release from prison begins to lead a double life. He becomes both the respectable, wealthy Montmorency and his degenerate servant, Scarper - while the police are baffled by a wave of mysterious thefts …