Eric Roberts, a bank worker from Surrey, joins MI5. He is given the alias Jack King and his job is to hunt for British Nazi-sympathisers.

Helena Bonham Carter shines a light on extraordinary stories from World War Two. Join her for incredible tales of deception, acts of resistance and courage.

A BBC Studios Podcast production for BBC Radio 4 and BBC Sounds.

Producer: Amie Liebowitz Executive Producer: Paul Smith Written by Alex von Tunzelmann