Scotland Yard is searching for Mister X. Will his pursuers catch him in the London fog? How will Mister X try to escape? Will the detectives find him in time? If they work together, they have a chance. Mister X will try to escape by bus, underground, and taxi. One player is Mister X, the others are the detectives. Mr. X moves secretly, but leaves a clue on each turn. With clever teamwork, the detectives can surround and trap Mr. X in time. But if Mr. X can slip away, he escapes and wins the game!