A young woman is found stabbed to death in the Catacombs. Since some parts of the Catacombs are a known hang-out for Goth teenagers and would-be Satanists, suspicion at first falls on those two groups. But the style of the killing suggests a sexual motive. The victim is identified as a DNA researcher in a lab, a repressed loner whose life under closer examination reveals that she frequented sex bondage clubs - the police thinks that maybe she was in the Catacombs for a sexual rendezvous. While the rest of his team is chasing the sex angle, Jo links the dead girl to some missing lab equipment - equipment he learns is used to insert DNA into living cells.