When the body of a girl is found, cut into three, DI Edgar Stephens recalls a magic trick that he saw as a boy. The illusion is called the Zig Zag Girl and its inventor, Max Mephisto, is an old friend of his. They served together in the war as part of a shadowy unit called the Magic Men, formed to use stage trickery to confuse the enemy. Edgar tracks down Max and asks for his help. Max is still on the circuit, touring seaside towns in the company of ventriloquists, sword-swallowers and dancing girls. Max is reluctant to get involved but he changes his mind when the dead girl turns out to be his former stage assistant. Another death follows, again gruesomely staged to resemble a magic trick, the Sword Cabinet. Edgar and Max become convinced that the answer to the murders lies back in their army days and the antics of the Magic Men. When Edgar receives a letter warning of another 'trick', he knows that they are all in danger. The Wolf Trap is the deadliest illusion of all, but who will be the next victim?