June 1940. As World War Two rages, Daphne Devine remains in London, performing each night as assistant to stage magician Jonty Trevelyan, aka the Grand Mystique. Then the secret service call. For, aware of Hitler's belief in the occult, the war office has set up a hidden cohort to exploit this quirk in the enemy's chain of command. Daphne and Jonty find themselves far from the glitz and glamour of the theatre, deep inside the lower levels of Wormwood Scrubs prison. Here, they join secret ranks of occultists, surrealists, and other eccentrics co-opted to the war effort. There is one goal: to avert invasion on British shores. Soon Daphne realises she must risk everything if there is any chance of saving her country.