Three years ago a former private spy came to our newsroom at Tortoise. He told an incredible story about infiltrating a campaign group, deceiving people for years but all the while being a 'double agent', before his world fell apart. And it all played out in the opaque world of corporate intelligence. Since then, journalist Ceri Thomas has been asking who Rob Moore really is and what his motivations were.

It's 2012 and Rob Moore goes 'into the dirt', undercover, to infiltrate a group of campaigners fighting for a ban on deadly asbestos. None of them knew they had a private spy in the camp. But it's hard to stay hidden forever.

Rob Moore says he can justify going undercover among anti-asbestos campaigners because he was following a Buddhist principle, turning poison into medicine. To this day he believes that if the people he infiltrated would really listen to his story they'd understand him differently. But does his story really stand up to scrutiny?