Early one morning

Fierce rivals, Englishman William Grover-Williams and Frenchman Robert Benoist, race their elegant Bugattis on the European race circuits. Not only is the World Championship in their sights, but they both fall for the charms of Eve Aubicq. But when war breaks out, both are signed up by Special Operations Executive for missions behind enemy lines in France, one of which includes investigating rumours of the manufacture of the lethal gas Zyklon B and how it is being used by the Germans. In a series of daring sabotages and assassinations, they cause havoc to the Germans, but finally their cover is blown and they are captured and tortured.