When recently promoted policeman Ferdy and his colleague Matt the Stat are called out to their first murder scene, they find a dead woman on the bank of the Thames. Her eyes have been gouged out and a tarot card -- 15 the Devil - has been stuffed in her mouth. Among the onlookers is the BMX Kid, a teenager who tells Ferdy about the curious swirling globe graffiti and the satanic rituals in Brooklands Parks. Discovering that the dead woman is a sex worker, Ferdy sends a man undercover to find why none of her friends have come forward. A second murder with the same modus operandi turns Ferdy's investigation upside down, but the mysterious BMX Kid glides into the station to once again offer information.