In May 1940, feeling the RAF needs every man to fight to Luftwaffe, Geoffrey 'Geoff'/'Boy' Wellum joins at 18, becoming the youngest ever Spitfire pilot. After an intense training, he soon bonds with the flying men of his squadron. In the air, danger is great, but on the ground drinks, sports and girls, in Geoff's case Sarah, provide great comfort. However in time, the casualties exact a grueling psychological toll, until his tour of duty is ended after 18 months.