Mary Gillespie is restoring the Col. Gillespie Circus to its former splendor after her father's death. With the help of her publicist boyfriend Jim, the sell-out crowds are returning to the big top. Egotistical equestrian star Senor Martinet, however, holds $60,000 of notes signed by the Colonel and due in 24 hours. When a mysterious shadowy figure is seen on the circus lot, and Martinet is murdered in the center ring during his performance, there are suspects aplenty, including Vindecco, Martinet's badly abused hunchback assistant.

Inspector Killany of the New York City police department is called in to investigate the murder of a subway passenger and the usual-and-unusual suspects climb on and off at each stop.