It is the end of the Prohibition, and the beginning of the Great Depression in the United States of America. The Stranger is a mysterious operative of a secret organization known as “Spookhouse”, founded by President Theodore Roosevelt to combat supernatural creatures. He investigates four cases, which can be played in any order and involve teaming up with a half-vampire to retrieve a powerful artifact from a castle in Germany, liberating a Wild West town from a zombie assault, fighting reanimated mobsters created by the mafia boss Al Capone in Chicago, and solving the mystery of a house with deadly traps.

Nocturne is an action game with survival horror elements. The game features 3D characters and pre-rendered backgrounds with fixed camera angles. The Stranger mostly fights with firearms, and has to confront monsters and mythological creatures. The player can opt to aim manually, or choose the auto-aim option from the menu.