Working-class Eddy Beane is a flight instructor in London. He successfully completes dangerous espionage missions and takes on society-girl June Stephenson as a student. Her ex-fiancé, Dudley Thane, is also a flyer, but upper-class and Cambridge-educated. When the Luftwaffe attacks England in 1940, Eddy and Dudley end up in the same Spitfire squadron. Aerial combat is intense, and both men show their mettle, but can they set aside class differences to fight together for the defence of Britain?