Police officers search for a man in Luton who disguises himself as a delivery driver to force his way into people's homes and commit brutal assaults. However, when the police investigation fails to make headway, the family of one of the victims launch a campaign for information on social media - which increases the likelihood of the criminal seeing he is at risk of discovery and going to ground.

Part one of a two-part report into the case of a man who sexually preyed on young people in Luton, which eventually became Bedfordshire Police's largest ever operation into historic abuse. The film begins with the work of a detective in the Child Sexual Exploitation unit, who discovers that a victim's testimony identifies a man who had been arrested eight times previously for sexual offences but had never been convicted.