A circus' black Panther is forced to attack two scientists by a former colleague of theirs, on behalf of the corporation for which all three had worked, and Ace's own panther Zina is blamed by the police. Ace, Cosmo, Lt. Vega, and the circus' trainer 'Yokiko' jointly recover the two panthers, defeat the mad scientist Dr. Pax of the Millix Corporation, and exonerate Zina.