Returning to Central City, from a morning jog across the continents, the Flash encounters a robbery, being perpetrated by a clown. Alerted to the Flash's presence by one of the incapacitated police officers, the clown goes on the offensive. The clown launches his pogo stick at the Flash, then flees in an old jalopy. The Flash easily fends off the clown's attack, quickly catching up to him. The shell of the jalopy falls away, revealing a souped up hot rod. Locking onto the Flash's heat signature, the discarded pieces of the jalopy come barreling towards him. Vibrating his molecules into intangibility, the Flash dives beneath the street, to avoid the collision.
Without missing a beat, the Flash resumes his pursuit. Just as the Flash is about to lay hands on the clown, he is pied in the face. The pie is saturated with ether, knocking the Flash out. A mysterious figure makes plans to steal 15 ounces of heroin from the evidence room, at police headquarters. The Flash, as police forensics scientist, Barry Allen, is called into a meeting with the Chief of Detectives, Captain Harvey Paulson. Allen learns that his graduate thesis paper has become the guiding inspiration for the Nephron Process. Allen is ordered to attend a meeting with Professor Gilbert Nephron, at the state penitentiary.
Allen calls home to break his dinner plans, incurring the wrath of his wife, Picture News reporter, Iris West. A mysterious woman looks over her shrine to the Flash, bemoaning the fact that she doesn't know what the Flash looks like underneath his mask. Allen arrives at the penitentiary, and attends a demonstration on aversion therapy. Nephron believes that criminals can be programmed to feel an abject aversion towards criminal acts, thus ending their threat to society. Allen has his doubts. Nephron's demonstration is broadcast to every cell in the prison. At the end of his lecture, Nephron asks for volunteers, from the prison populace, to undergo his process.
Any man that does will be granted a full pardon, by the governor, regardless of his crimes. Only one man volunteers, murderer Clive Yorkin. At police headquarters, a pair of shadowy figures move the heroin, from the evidence lock-up to Allen's laboratory, disguising it among the bottles of chemicals. The next morning, Allen finds his wife is still not speaking to him. En route to work, Allen, as the Flash, sees a large, gaseous "HA HA" floating over the city. Further investigation leads to a steam powered calliope, rolling down the street. The Flash spies a tuft of the clown's hair beneath a manhole cover. Creating a powerful updraft, at super-human speed, the Flash pulls the clown from the sewers.
As the clown is lifted into the air, the Flash notes that he's attached to a coiled metal spring. As he rises higher into the air, a cluster of dynamite, tangled in the coil, reaches street level, and detonates. The Flash is able to avoid the primary explosion, but finds himself caught in the blast wave. Vibrating his molecules at super-human speed, the Flash is able to partially slip through a brick wall, instead of slamming into it. With the molecules of his legs merged with that of the brick wall, the Flash is a sitting target. A fact the clown takes advantage of, by firing missiles at the Flash, from the cannon-like pipes of the calliope.