Bad blood exists between Bill Steele and Frankie Stanton, the leading contenders for the heavyweight title, and a grudge match is scheduled. Steele's knockout victory is tainted by his opponent's untimely death, ostensibly from a concussion caused by hitting the canvas. A post-mortem reveals that poison was somehow introduced into a cut above Stanton's eye although it is unclear how and why. Gambling might seem to be the motive as several of the principle suspects, gamblers Clipper McCoy and Nick Crowder, Stanton's shady manager Jerry Connors, and fight promoter Philip Benton, all seemed to have made wagers on the fight. Benton's spoiled daughter and female reporter Penny Kendall are vying for the affections of Steele, who is now slated to fight for the championship against pugnacious Biff Moran. Lt. Riggs of New York Homicide and Moto, who were spectators at the fight, go on the trail of the murderer following the autopsy results. Moto's prime suspect is a shadowy character named John Howard, who collected on huge bets in four different Midwestrern cities after the Stanton fight. Discovering his real identity will be a key to Moto's TKO of the killer.