We like to think we know the story of how Britain went to war with Germany in 1939, but there is one chapter that has never been told. In the early 1930s, a group of young, queer British MPs visited Berlin on a series of trips that would change the course of the Second World War. As Hitler rose to power, they watched the Nazis arrest their gay and Jewish friends, send them to concentration camps and murder them.

These men were some of the first to warn Britain about Hitler, repeatedly speaking out against their government's policy of appeasing him. Prime Minister Neville Chamberlain hated them. Branding them 'the glamour boys', he had them followed, harassed, spied upon and derided in the press. They suffered abuse, innuendo and threats of de-selection. At a time when even the suggestion of homosexuality could land you in prison, the bravery these men were forced to show in their personal lives gave them extraordinary courage in public. Adept at hiding their true nature, some became talented spies, while others witnessed the brutality of Hitler's camps first hand. Four of them died in action. And without them, this country would never have faced down the Nazis.

Based on years of archival research, this is a story of unsung bravery at a defining moment in Britain's history.