A secret, high-technology international agency called SHADO defends Earth from alien invaders.

As the Earth wrestles with its agonizing birth, the peoples of this barren and desolate world struggle to survive. Driven by animal instinct they compete against the harsh conditions, their giant predators, and warring tribes. When two people from opposing clans fall in love, existing conventions are shattered forever as each tribe struggles for supremacy and Man embarks on his tortuous voyage of civilization.

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.