Elizabeth and Timus are negotiating with a representative of the Sorsons - a race of advanced non-humanoid aliens - to try to end the war between them and the Thargons, but their attempts are unsuccessful. Elizabeth contacts the Lab and tells her fellow Tomorrow People that the Galactic Federation is powerless to prevent the Sorsons and Thargons entering Earth's area of closed space. After the Sorsons land on the moon and begin construction of a base, the President of the United States of America sends a space-shuttle to investigate. Tim detects the arrival of the Sorson and Thargon spaceships, and John and Mike decide to jaunt up to try to stop any fighting; but the battle begins before they can act, and the American space-shuttle is caught in the middle. John and Mike save the crewmen, Evans and Ricardo, by using matter transporters to send them back to their base; however, despite contacting both fleets, they are unable to prevent the battle from ending.

Elizabeth returns to the Lab, just as General Vishishnu and his Sorson fleet enter Earth�s atmosphere; one ship lands near the White House and the Sorson representative promises to help the President defend the planet, and gives him a Barluminite raygun to stop the Tomorrow People interfering without harming them. John and Elizabeth jaunt to the Galactic Trig to discuss the Sorson landing on Earth, but the committee�s lack of interest angers John, and he is charged with contempt by the chairman, arrested, and sent to the Proctor Detention Centre with his telepathic powers removed. Mike and Hsui Tai jaunt to the White House, but the President accuses them working for an alien power and withholding advanced technology, and shoots Mike.

The President imprisons Mike and Hsui Tai. The Sorson General, Vishishnu, begins training American pilots, including Evans, so that they can defend the solar system. Andrew jaunts to the Oval Office to rescue his friends, but is captured after the President uses the Barluminite raygun on him. But Andrew is only pretending: he ducked when the gun was fired, and he uses matter transporting bands to return to the Lab with Mike and Hsui Tai. Andrew suggests threatening the Trig with a Sorson spaceship in order to rescue John, and they jaunt onto one of the spaceships. Eliciting the aid of Evans, they travel to the Trig, where an artificial intelligence refuses to release John until his case has been heard. Evans opens fire, and the Chaircreature releases him. The Tomorrow People return to the Lab, where Tim, defying instructions from the Federation, informs them that their membership has been suspended. Meanwhile, the Sorson General is furious that Evans has taken a ship and destroyed other Sorson ships, and tells the President that his fleet will depart, leaving the planet at the mercy of a Thargon fleet heading for Earth.

Earth faces danger from two directions: the Thargons and the Sorsons. The Tomorrow People must somehow defeat them both to save the planet.