A group of thugs is muscling an old man on a city street, attempting to extort loan shark money from him. Firestorm, the city's newest super-hero flies down and easily apprehends the goons. He then begins showing off his powers to the delight of several onlookers. One woman in particular, astonished by his appearance, faints before his eyes. Firestorm flies off and separates into Ronnie Raymond and Martin Stein. Ronnie returns home while Martin returns to the Hudson Nuclear Power Plant.

At the Raymond home, Edward Raymond is watching a news broadcast featuring Firestorm. He expresses his disapproval of this latest string of vigilante heroes.

Martin Stein arrives at the Hudson Power Plant and tries to get many of the destroyed systems back on line. Two identical villains calling themselves Multiplex burst into the room and attack Stein.

Miles away, Ronnie Raymond feels the impact of Multiplex's blow against Stein's jaw. He theorizes that the two bonded together even when they are separated from the Firestorm persona. Ronnie attempts to prompt the transformation from a distance and turns into Firestorm. Multiplex has already absorbed massive amounts of atomic radiation by the time he arrives at the power plant. With the added power, he successfully beats Firestorm back. Their fight carries out into the streets, garnering the attention of Superman.

Superman flies down and introduces himself to Firestorm. He sizes him up, in order to see if the young man is actually the hero that he claims to be. Firestorm is humbled to be in the presence of Superman – so much so in fact, that he completely forgets about Multiplex. Multiplex takes advantage of the distraction and gets away.

Firestorm tracks him down and finds him at State University. Multiplex has broken into a campus radiation vault and is in the process of stealing even more power. Firestorm cuts off the villain's radiation supply by turning the plutonium compounds into phosphorous. With Multiplex's powers on the wane, Firestorm easily knocks each iteration of the villain out with one solid punch to the jaw. He removes their masks to reveal that they are both in fact Danton Black, Martin Stein's former research assistant. Danton was present at the Hudson Nuclear Power Plant during the explosion that fused Ronnie and Stein into Firestorm. In Black's case, however, the nuclear radiation had a fission effect. Rather than merging his body with another, it granted him the ability to split himself into two corporeal beings. The authorities arrive and take Multiplex to the Downtown Medical Center.

Later, Firestorm meets with Superman again. Superman thinks the young hero has a lot of energy and charisma and that he may one day prove himself worthy of joining the ranks of the Justice League of America.