The team investigates the murder of Dominic Morton a pedophile who was recently released from prison. He's found in his home stabbed and emasculated the result, the police believe, of vigilantes. When they identify calls made from Morton to a Peter Taylor they also find that both men look exactly the same. The puzzle becomes a mystery when they are unable to locate Morton's victims or any probation records for him. When they learn he was an undercover police officer trying to infiltrate a pedophile ring, the police start looking for a rent boy he was trying to get information from. The case comes full circle when they learn another police officer may be involved.