When body parts and medical waste are found in Wetherton lake, Dalziel and DC Lateef investigate the disappearance of missing nurse Leanne Proctor, last seen three days ago by her flat mates. Meanwhile, Pascoe is seriously injured whilst pursuing a suspect through an underground maze of tunnels, leaving Dalziel wondering if he will make it through. As the prime suspect for Leanne's murder looks certain to have attacked another nurse, Dalziel wastes no time in setting up a sting by trying to catch him in the act - using staff nurse, and Pascoe's latest conquest, Shannon, as bait. Convinced they have their prime suspect by the balls, Dalziel and Lateef are distraught to discover CCTV footage, which places him in Oldham at the time of the killing. And when Shannon discovers that a withdrawn drug is still being prescribed to some epileptic patients, the real culprit of murder is revealed.