Lightner, who has previously paraded a planetary zoo and similar entertainments, takes Pa Jory's interstellar circus to Furioso, from which bareback rider Gratia side-trips to an unexplored sister planet and returns with a sort of clawed horse she names Calico--for the similar, prehistoric earth creature Chalicothere. Jonathan, a homeless local twelve-year-old, soon attaches himself to the circus and especially to Calico, who learns her acts exceptionally fast--so fast that Furioso's strong-arm Colonel Dagan wants to confiscate her for experiments. Lightner plots the obligatory perilous trek for a fleeing Calico, Jono, and Gratia, and the issue of the animal's custody escalates to the level of a military coup, no less. Happily for the circus, the rebelling Colonel gets his just deserts at the hands (?) of a huge, voracious Blob--but far creepier than the Blob is the ugly, snakelike creature discovered to be living in Calico's back (""symbiosis,"" explains the circus vet) and responsible for her superior intelligence. Lightner makes no philosophic point of this peculiarity, but simply leaves it to protrude from the innocuous story long after the colonel stops thrashing and the circus departs.