The Hollywood Reporter notes that the film’s storyline is inspired both by the world created for the original game and the best-selling comic book series that accompanied it, “Injustice: Gods Among Us: Year One.” The comic book was written by Tom Taylor and first released in 2013 to coincide with the game’s release.
The comic book dives into the specifics of why Superman begins his quest to establish his totalitarian regime on Earth and is filled with moments that fans need to see in the animated movie. In the comic’s alternate DC Universe, Joker tricks Superman into causing the death of Lois Lane and then the destruction of Metropolis by a nuclear bomb. The corrupted superhero then decides that Earth would be better off under his total control, leading to his quest for world domination, while Batman enlists insurgent elements of the Justice League to stop him, also according to THR.
The announcement also mentions some of the voice cast for the film. Superman will be played by Justin Hartley, Batman will be voiced by Anson Mount, and Laura Bailey will appear as Lois Lane. On the other side, Kevin Pollak plays Joker, while Gillian Jacobs voices Harley Quinn. The film, produced by Warner Bros. Animation and DC, is expected to arrive in the fall of 2021.