Guest Stars El Anthony as Mark De Costa Jonah Collier as Young Robert Napper Deka Walmsley as DCI Mick Wickerson Charlie Carter as DC Martin Long Anya Cooke as Young Napper's Sister Katie Buchholz as Rachel Nickell Maria Louis as Young Napper's Mother Tom Colley as Young Napper's Father William Owen as Journalist Stuart Cooke as Mr Wood Stewart Allen-Smith as Policeman at Door