While mainland Britain shivers in deepest winter, the northern island of Fara bakes in the nineties, and the boys at the Met station have no more idea what is going on than the regulars at the Swan. Only a stand-offish visting scientist realizes space aliens are to blame.

Freddie, a motor mechanic, rescues a baby, and twenty years later he offers to become responsible for him - Tony - when he is put on probation for petty theft. Tony abuses his kindness by involving Freddie's two adolescent children in a bank robbery, in which he panics and kills the cashier. With his associate, Spud, and the children, Harry and Monica, he makes for London.

In 1940, the Royal Air Force fights a desperate battle against the might of the Luftwaffe for control of the skies over Britain, thus preventing an attempted Nazi invasion.