BBC Sounds, Music, radio, podcasts.

We're taking a step away from the headlines today and bringing you an episode that we've actually been cooking up for a while now.

Now, I need to be upfront. This is a story about the darkest part of humanity.

But it's also a story about people around the world finding ways to work together,

which in these times is worth talking about.

It's a story of how law enforcement agencies work across time zones and borders to rescue children from abuse.

From the BBC in London, I'm Asma Khalid.

And today on the global story, we hear from a man who has spent the past two decades,

making it his mission to hunt down the child predators who populate the darkest corners of the internet.

Music predators who populate the darkest corners of the internet. Before we dive into today's show, I just want to let you all know that, as you might imagine,

this episode includes details of child sexual abuse.

For the last five years, our colleagues at the BBC World Service have followed

Greg Squire and other agents around for a big investigation. I'm part of Homeland Security

Investigations, and we specialize, our group specializes in crimes against children. And,

you know, the work has changed and evolved throughout my career, which started in 2007.

And, you know, our job is to locate these children, you know, and to minimize the amount of time between when they're abused and when we can find them and rescue them.

You have a job that I cannot imagine doing. So I've got to ask why you wanted to get involved with this work.

I was in the Army directly at a high school. When I got out of the service, I began working for the Postal Service. Doing that, I was going in a night school. I delivered mail. Yeah. Okay. It was very stable, two young kids at the time. Yep. And so that stability was very important, a steady income. And then I just started going to night school. I knew I wanted to do something different. I wasn't, you know, little boys grew up to want to be postman, I don't think. I don't know.

My little boys are obsessed with bail-down comes by, deliver some mail.

The trucks are pretty cool. The shorts are kind of nice. You know, there are some benefits. But you realize it wasn't for you. So you wanted to do something else. Yeah, it just wasn't for me, you know. So when I joined Homeland Security, I, you know, I really didn't know what we were getting into.

You know, I didn't know much about the crime or how it was investigated or any of that type of stuff.

I hadn't had any exposure to it.

...