Jupiter Monk is the galactic carnival's animal trainer - but one by one his animals die unable to adapt to the conditions of a new world every few days and Monk sets off to find a new attraction for the act. What he finds is a sentient alien who looks like a savage animal and the two of them come up with a scheme: on worlds where the audience resembles Monk he will be the animal tamer and on worlds where they resemble the alien they'll switch roles. It works beautifully for awhile and then things begin getting out of hand. 'Way out of hand in a nightly contest that threatens to tear the carnival apart.