Firestorm attends the opening of the new Science Center established by Martin Stein's old college roommate Mister Terrific until it get crashed by Calculator. When Calculator hacks Mister Terrific's T-spheres and separates Firestorm back into Ronnie Raymond and Martin Stein, it up to Martin Stein and Mister Terrific to work together to free Ronnie Raymond and defeat Calculator.
The Justice League is back, 'with lightning-paced action and heroics'. This show will be including everyone: Superman. Batman, Wonder Woman, Hawkman, Green Arrow, Zatanna, Shazam, the Flash, Blue Beetle, Plastic man, Martian Manhunter, Lobo, Zatanna, the Demon, Dr. Fate and fan favorites like Harley Quinn and many more. Justice League Action, will also reunite the Batman Animated Series voice talents of Kevin Conroy as the Batman and Mark Hamill as the Joker.