After they rescue Lucy, Greg and Pete discover the dark web community is even bigger than they thought. There are hundreds of websites each sharing different images of different kinds of child sexual abuse. Overwhelmed by what they have found online and the sheer scale of the problem, Greg makes a decision to go undercover. He will go online on the dark web and talk to the paedophiles directly. They have to do everything they can to try to stop the abusers.

This podcast includes some upsetting scenes and discussions of child sexual abuse.

For further information on the issues raised in the programme, contact support organisations in your own country. For a list of organisations in the UK that can provide support go to bbc.co.uk/actionline.

Reporter and Presenter: Sam Piranty