The Avengers visit a hospital mortuary where Steed identifies the body of an agent, Williams, discovered in the ashes of a burnt-out fishing hut. Among the dead man's belongings is an unusual chess piece. They visit the scene of the crime and as Steed pokes about in the ashes, he is discovered by Bush, who says he is trespassing. The hut belongs to his partner, Captain Slim. Steed visits Captain Slim, but is unable to find out how the fire started. By the way, this is the last episode with Cathy Gale.