An alien presence has arrived on Earth. Lethbridge-Stewart has been dispatched to determine the nature of the new arrival.

The Fifth Operational Corps is not the only one interested in the visitor. The race is on to establish diplomatic relations with the extra-terrestrial, and a top-secret military team from the Soviet Union are one step ahead of them…

If either side can successfully form an alliance with the creature, it could turn the tide of the Cold War forever, bringing it to a sudden and unexpected end – with the victor controlling the future of mankind.

Lethbridge-Stewart must call upon the brightest and the best to ensure that Britain is successful in its negotiations, as the alternative is simply too terrifying for him to contemplate… an alien menace – allied to the Soviet Union!