Sargon the Sorcerer has apparently killed Flash.
Picture News reporter, Iris West, convinces her husband, police forensics scientist, Barry Allen, to take a vacation. Allen, as the Flash, uses his Cosmic Treadmill to travel to the 23rd Century. Returning seconds later, the Flash seems noticeably well-rested. Then he collapses. West gets the Flash, as Allen, to a hospital. Allen slips into a coma, leaving the doctors baffled as to the cause of his condition. Meanwhile, in the 25th Century, Eobard Thawne, the notorious Professor Zoom, sits in his cell, watching old gangster movies. Thawne is contacted by Sargon The Sorcerer, and offered a chance at escape. Sargon draws Thawne back in time, to the 20th Century.
After handing Thawne his Reverse-Flash costume, Sargon reveals that, after spending the last two decades fighting crime, he wishes to pursue a more villainous path. Sargon asks Professor Zoom to reveal the secrets of time travel to him. Professor Zoom refuses, and races away at super-human speed. With the power of his Ruby of Life, Sargon pulls the bones of the Flash from some future grave, into the present. The Flash's skeleton is found in a hole by a trio of young boys. Sargon reveals to Professor Zoom that he has slain the Flash, thinking that, without purpose, Professor Zoom will teach him the ways of time travel. Professor Zoom again refuses, and speeds away.
Moving faster than the human eye can see, Professor Zoom trails West to the coroner's office. When West identifies the bones as actually belonging to the Flash, she breaks down in tears. Convinced of the Flash's death, Professor Zoom returns to Sargon. Instead of revealing the secret to traveling in time, Professor Zoom tricks the sorcerer into condemning himself to the netherworld, Chimano. With the Flash no longer a threat, Professor Zoom embarks on a crime spree that will span five centuries, and cover the entire globe. Allen awakes from his come, and departs the hospital. Donning his Flash costume, Allen is just about to race for home, when he collapses again.
Upon regaining consciousness, the Flash hails a taxi, to carry him home. Overhearing that Professor Zoom is at large, the Flash exits the cab, and races off after his evil counterpart, only to suddenly disappear. Sargon the Sorcerer, using his Ruby of Life, has called the Flash to him. With the Flash holding onto the Ruby of Life, the Scarlet Speedster is able to align his, and Sargon's, vibrational frequencies with that of the mortal realm, allowing them to escape Chimano, and return to Central City. Sargon passes out from the effort. The Flash tracks down Professor Zoom, outside the Flash Museum.
The Reverse Flash hurls the loot, that he's gathered from around the planet, at the Flash. Using a shrink ray, Professor Zoom miniaturizes the Flash. With the Flash his prisoner, Professor Zoom continues his centuries spanning crime spree, ending in the 25th Century. Using the Ruby of Life, which he's been holding onto the entire time, the Flash escapes. After quickly defeating the Reverse-Flash, the Flash regains his normal stature, and returns to his proper century. Sargon vows to take back the Ruby of Life from the Flash. Having been cured of the disease he picked up, on vacation in the 23rd Century, an exhausted Flash, as Allen, returns home, and collapses into bed. Much to the chagrin of West, who is ready to start her vacation.