When investigative journalist Aric Toler saw a handful of supposedly fake classified documents online, he had a hunch - what if they were real? The only way to find out was to hunt for the original source.

It was a journey that took him through the deep internet, beyond the reach of search engines. He scoured through chat forums about SpongeBob SquarePants, infiltrated servers named after edgy memes, and found a vital clue in screenshots of a video game about zombies. Eventually, Toler got his man - and his identity was not at all what you might expect.

At the heart of this story is the chat service Discord - a casual, conversational space without which, Toler thinks, his unlikely leaker would never have posted classified documents online.

A Tempo & Talker production for BBC Radio 4