Solo gets an unwelcome young companion (Kurt Russell), a ten year old who wants Solo to marry his widowed mother, in his efforts to find the source of a deadly chemical that killed an entire Scottish village. In a race to find the source with General Yokura (Leonard Strong), Solo eventually uses a ring on the finger of a statue to pinpoint a cave where the deadly chemical has leaked from, but has to use his wits to escape when he is trapped there by Yokura and his men.

A dying UNCLE agent warns Napoleon and Illya that a group of supermen is being bred by THRUSH. The duo discover a school set up by the enemy organization in Mexico, who has already produced 7 emotionless killer students! As a graduating exercise, one is chosen to eliminate Solo and Kuryakin after they follow the boy to Austria.