The threat of Armageddon forces an alien race to look upon Earth as a new home world for their people. Against their superior technology Earth must rely upon Sally Jameson, a scientist working for NASA. She becomes convinced that she has uncovered an alien plot against the people of Earth, she sets out to find the necessary proof to convince the authorities. However, she soon comes to the attention of the aliens who decide to kill her before she can convince her Uncle, a Texas Ranger, of the danger coming from deep space. As she battles to win so the aliens use ever more terrifying weapons in a bid to keep their presence a secret, but help comes to her from a surprising source. The fight is on, the fate of the people of Earth is the stake, the winner of this galactic contest takes all.