The squad investigates the murder of Natasha McKay, found dead on the banks of the Thames. She was severely beaten but actually drowned. Natasha was an attractive woman who modeled in the soft porn industry and had frequently been a page 3 girl. Her wealthy property developer husband has a cast-iron alibi for the time she disappeared but DC Rosie MacManus has her own reasons for pursuing him, which causes DI Friend to question her judgment. The investigation focuses on Simon Crookshank, a friend from her schooldays as the police conclude they were having an affair.