Warning: this episode includes discussions of child sexual abuse and upsetting scenes. The BBC has been following a global team of undercover officers as they investigate the most hidden corners of the internet to stop those who exploit and harm children. A dedicated network of specialist investigators has successfully tracked and caught serial paedophiles who operate across the dark web with the same sophistication and secrecy as international organised crime syndicates. We speak to Special Agent Greg Squire who has dedicated his life to rescuing children who might otherwise never be found. His story is featured in the BBC documentary The Darkest Web and the BBC podcast World of Secrets: The Darkest Web. 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. The Global Story brings clarity to politics, business and foreign policy in a time of connection and disruption. For more episodes, just search 'The Global Story' wherever you get your BBC Podcasts. Producer: Xandra Ellin Executive producer: James Shield Mix: Travis Evans Senior news editor: China Collins (Photo: Greg Squire in The Darkest Web: Inside the internet’s most hidden corners to save kids – BBC World Service Docs)