From the moment they decide to make a couple of quid from taking on a young Belgian euro-exchange drummer, in April 1939, the easy-going, lifelong friends in Stanley South's big band are in trouble. They are pulled into a plan to steal, move and hide great treasures of Art, but think they've landed on their feet, making good money working for the British government; travelling abroad to play their rascally hot, tip-top swing music to help support resistance against the Nazis. The plan remains invisible to them, even though it pushes them across the thinnest of thin ice, and costs Lester a testicle.