n 2013, the newly created National Crime Agency uncovered one of the biggest online child abuse cases ever seen in the UK. Hundreds of British teenage boys had been duped into sending indecent images of themselves to what they thought was a teenage girl online. Many were blackmailed into sending more and more images, with chilling threats made against them by an unknown abuser. With unprecedented access inside the National Crime Agency, episode one re-tells step-by-step the hunt to find this offender - a journey that would take investigators half way across the world - and the race against time for social workers to try to locate and protect all the victims, with the numbers ever increasing.