The duo look into the murder of an eight-year-old boy, coming up against a pedophile who cruelly deceives his victim's family. Dom's HIV test comes back negative, so he sets out to celebrate - only to endanger his own life and jeopardize Rachel's sergeant's exam in the process. Janet tells Andy she is having second thoughts about their brief liaison, but he finds her decision hard to accept.

• Sally Wainwright

• Rupert Graves
• William Ash
• Ian Mercer