At the beginning of 1937, the British monarchy was in a state of turmoil. The previous king, Edward VIII, had abdicated the throne, leaving his unprepared and terrified brother Bertie to become George VI.
Meanwhile, as the now-Duke of Windsor awaited the decree that would allow him to marry his mistress Wallis Simpson, he took an increased interest in the expansionist plans of Adolf Hitler.
As double agents and Nazi spies thronged the corridors of Buckingham Palace, the only man the king could trust was his prime minister, Winston Churchill.
But they faced a formidable, even unbeatable, adversary: his own brother.
