We focus on the part of the internet that most people don't know about.

It's called the dark web.

Undercover in the furthest corners of the dark web,

US special agents are on a mission to locate and rescue children from abuse.

Move in now.

Police!

From the BBC World Service, World of Secrets, the darkest web follows their shocking investigations.

Listen on BBC.com or wherever you get to your BBC podcasts.

Before we begin, this episode refers to child sexual abuse.

It contains strong language and language some listeners may find offensive.

I believe 100% that I was abducted the first time. The first time I was taken, I was abducted.

Because the first time when I was taken from school to his house, nobody knew I went. Nobody knew I went. Nobody.

The same year, eight-year-old Vishal Marotra was abducted from the streets of West London,

an 11-year-old boy, also of South Asian heritage, and also from West London, started being

sexually abused by a paedophile who worked at his boarding school in Sussex.

One weekend, the man took him from the school to the paedophile's own mother's house.

He just took me, that was it.

Said I was spending the weekend at his house.

And I remember that so quickly.

I remember that.

And when I hit back 16 and 1717 that kicked in and I thought to myself

look how far

...