The Professor eagerly awaits the arrival of a Doctor Doyle. Upon arrival, everyone is surprised to find that Doyle is actually a woman. Doctor Robin Doyle had come to Africa to study Keewazi's tribe with the Professor. While studying, they find some of the older men to have quite startling ages (from 500 to 700), and learn about a great fountain. The professor, who feels he's too old for Robin, secretly sets forth to find this fountain.

Doctor Robin Doyle returns to the jungle with her nephew Ian, a bookish child with few friends who spends his time collecting butterflies. While Robin and the Professor spend some quality time "spooning", the task of entertaining Ian falls to Tarzan, whom Ian sees as a much-needed role model. Lacking any other experience, Tarzan fills the day with activities he enjoyed as a child, and it's not long before the boy has discarded his formal trappings for a loincloth. None of this sits quite well with Jane, who worries about the dangers of a small child swinging recklessly from tree to tree—and what the good doctor will say when she finds out.