Welcome back, history enthusiasts. I'm Philip Champion, and this is WW2 Stories. Today, we're going to enter the shadowy world of espionage and counter-intelligence, where nothing is as it seems and trust is the most dangerous currency of all. This is a story of one of the most audacious and successful deception operations in military history—a game of chess played with human pawns, where British intelligence masters turned their enemies' own spies against them.