The planet Ygam is inhabited by the giant Draags, androids who live by meditation. Their children's favourite company is the WHO, little men from a devastated planet and used by the Draags as pets. Terr, raised and guarded by Tiwa since birth, senses that the knowledge of giants is through messages that are picked up by a kind of electronic headset. When Tiwa is initiated into meditation, Terr escapes carrying a cap, and is housed in a community of his fellow men, who have taken refuge in a tree to escape the continuous extermination carried out against their damage. In one of these raids, the surviving WHO take refuge in an ancient missile depot and, thanks to the knowledge gained with the headset, restore its use. Years later (only weeks in the life of the Draags), the WHOs led by Terr reach the Wild Planet where they uncovered the secret of Draags' vitality...