The JSA attends the National Society of Inventors Show at the Palace, when their friend, inventor Dr. Swanley is found dying, and the blame for his murder is laid on news reporter Weldon, even though the murder weapon cannot be found. Swanley's weird invention and papers are turned over to Swanley's friend, Pomar, and the All-Stars visit Pomar to learn of the invention's use, which turns out to be a time chute. The JSA reasons someone murdered Swanley and then dropped the gun into the time chute, and they have only two hours to recover the gun and murderer before Weldon is executed.; Flash and Black Canary travel back through the Time Chute to the 14th Century, where the gun in question is in the possession of the Khan. After amusing the Khan to win a favor, the Flash secures the gun, then he and the Canary must battle guards to keep it. Then the gun suddenly disappears from Flash's hand. Meanwhile, Wonder Woman and Dr. Mid-Nite land in Europe in the 5th Century, and are taken prisoner, coming before Attila, who has the gun in hand. Through trickery, the JSA duo secure the gun after battling Attila's Huns, but the gun disappears from the Man of Night's hand!; Hawkman and the Atom land in ancient Rome in the year 71 B.C. and notice a poster telling of gladiator bouts being held, and one gladiator, Spartacus, will be using a newly discovered weapon. The duo head for the arena where the Atom spots the gun and takes it, but is set upon by the other gladiators. Winning the battle, the duo speed away with the gun, which vanishes. G.L. is dropped off in 9638 B.C. and eventually meets with the Queen of Atlantis, who shows him the murder gun. An sudden earthquake allows G.L. to secure the gun and his ring keeps it from disappearing again.; G.L. uses his ring to pick up the other members from their Time Ledges, and a quick visit to the Governor with the gun saves Weldon's life. The JSA is asked to return the Time Chute to Pomar, and when they do, they discover Pomar to be Swanley's killer. He uses a new ray to destroy their will to live, but Dr. Mid-Nite pulls a trick on Pomar by causing the rays of the weapon to play on Pomar, causing him to commit suicide.