Somewhere in America, a twelve year old girl is being abused in her own home. Her abuser is sharing photographs of her with a vast community of child abusers on the ‘dark web’ — an encrypted corner of the internet where users are untraceable. But, hidden amongst the paedophiles, are two men whose job it is to try and find her: US Special Agents Greg Squire and Pete Manning. For more than seven years, BBC Eye journalist Sam Piranty was granted rare access to follow their work, observing the extraordinary lengths they will go to hunt down offenders and rescue children. Every detail matters, and every decision has consequences. They will not look away. The race is on.

Season 11 of World of Secrets, The Darkest Web, is a BBC Eye investigation for the BBC World Service.