While Esteban Miranda, the man who once impersonated Tarzan, escapes from Obebe’s village, Tarzan crashes during a solo flight and enters the unknown country beyond the Great Thorn Forest, where he encounters the Alali and the tiny people of Minuni. Befriending the rulers of Trohanadalmakus, he joins their war against the rival city of Veltopismakus but is overwhelmed, captured, and carried into the enemy city. There the scientist Zoanthrohago uses Tarzan in an experiment that reduces him to the size of the Minunians, leaving the once gigantic ape-man vulnerable in an entirely new world of danger.