DC Shona Birkby from Bedfordshire Police's Rap and Serious Sexual Offences team analyses a video of a couple having sex without knowing they are being filmed. As she forensically examines her suspect, she explains how she believes he is regularly prowling the streets filming women in compromising positions without their consent to get sexual thrills. The case takes a sinister turn when, within weeks of the video being taken, police receive a call from a nightclub where door staff believe a woman has been attacked.

Part one of a two-part special revealing the story behind a brutal double murder, when one man is found dead in the road outside a pub while another has multiple stab wounds. Despite both men being pronounced dead at the scene, no one in the close-knit community of Houghton Regis has so far come forward to reveal who is responsible.