The Flash, tormented by a psychedelic creature, ends up in a parallel world.
Police forensics scientist, Barry Allen, is attacked, in his laboratory, by a fantastic, psychedelic creature. Allen, as the Flash, fights back, only to be forcibly ejected from the building. By the time he recovers, the creature is gone. At home, the Flash, as Allen, is sitting down to dinner with his wife, Picture News reporter, Iris, West, when the creature attacks again. Allen and West seek sanctuary in a nearby fallout shelter. Allen is about to engage the creature, as the Flash, when it, once again, disappears. Allen, as the Flash, pays a visit to the Flash Museum, only to find it being robbed.
The Flash is seconds away from subduing the thieves, when the creature attacks again. The Flash gets the thieves to safety, then turns to face the creature. After one punch, the creature fades away. Suddenly, an alien being appears before the Flash. The alien identifies the creature as a "Nok". The alien was transporting the Nok, along with other alien wildlife, to it's home world, when a malfunction in it's spacecraft forced it to land on Earth. The alien has managed to recapture the Nok three times, but each time the Nok has escaped again.
The alien gives the Flash 6 hours to subdue the Nok, at which time the repairs to the alien's craft will be complete, and it will be departing. The Flash turns the thieves over to the proper authorities. Suddenly, the Flash begins speeding up uncontrollably. The Nok rams the Flash from behind. The force of the impact, coupled with the Flash's extreme velocity, is enough to hurl the Flash across the dimensional void, to a parallel Earth. The Flash awakens on the floor of a warehouse, in the town of Willowdale. His costumed appearance immediately draws attention, and soon a crowd has formed around him.
The Flash is baffled by the crowd's reaction to him, until a young boy presents him with a Flash comic book. The Flash is amazed that the comic chronicles a prior adventure, down to the most minute detail. The Flash realizes that he is on a parallel Earth, one where he exists only as a fictional character in a comic book. The Flash determines that the power of a Cosmic Treadmill might just be enough to get him back to his own Earth. With only a few dollars in his pocket for supplies, the Flash heads to New York City, to speak with the editor of the Flash comic book, Julius Schwartz.
The Flash, as Allen, meets with Schwartz, who dismisses his wild claims. At super-speed, Allen puts on his Flash costume, right before the editor's eyes. Convinced, Schwartz heads out to garner the materials the Flash needs to build the Cosmic Treadmill. The Flash assembles the Cosmic Treadmill in Schwartz's office, then uses it to return to his own Earth. Almost immediately upon arriving, the Flash is attacked by the Nok. Vibrating out of it's grasp, the Flash determines that the Nok has been feeding on the invisible aura that protects his body from the heat of friction.
The Flash races to his laboratory, and builds a weapon that projects the same aura radiation that surrounds his body. Firing on the Nok subdues the creature, as it basks in the radiation. The alien arrives to take possession of the Nok. The Flash hands over the aura-radiation gun, so that the alien can continue to pacify the Nok, on the return journey home. At home, the Flash, as Allen, ponders the notion of being a fictional character on another Earth. On Earth-Prime, Schwartz ponders the magnitude of his meeting with the Flash, while regarding the Cosmic Treadmill left in his office.