High school senior Clifford "Kip" Russell is determined to get to the Moon, but the price of a ticket is far beyond his reach.

His unorthodox father suggests he enter an advertising jingle-writing contest; first prize is an all-expenses-paid trip there.

Kip reluctantly decides to return his space suit for a cash prize to help pay for college, but puts it on for one last walk.

Wormface has two human flunkies ("Fats" and "Skinny") who assisted him in initially capturing the Mother Thing and Peewee, the latter a genius and the daughter of an eminent scientist.

The Mother Thing speaks in what sounds like birdsong (illustrated by a few musical notations), but Kip and Peewee have no trouble understanding her.

Once Kip is well, he, Peewee, and the Mother Thing travel to a planet in the Lesser Magellanic Cloud, to face an intergalactic tribunal, composed of many advanced species that have banded together for self-protection.

The Mother Thing and a representative of another race argue that the short-lived species are essentially children who should be granted more time to learn and grow.

Floyd C. Gale wrote that the book "is possibly the most unabashedly juvenile of Heinlein's long list ... Great for kids, chancy for grownups who don't identify readily with adolescent heroes".

The cover for one of the French editions (Presses Pocket, 1978) is by notable science fiction illustrator Jean-Claude Mézières.