the film picks up where the end credits scene of Man of Steel 2 ends with Doomsday arriving outside Metropolis and begins his reign of destruction. Superman hears of the danger and flies from his Fortress of Solitude to intercept. the film is told thru the perspectives of everyone EXCEPT superman, as he battles against doomsday, slowly losing ground as he advances on Metropolis. Wonder Woman, Aquaman, and Martian Manhunter join the fray to try and help Superman stop Doomsday as the government scrambles its forces to assist. As this unfolds, Batman and Alfred formulate a plan of action as they figure out how to defeat an unstoppable creature that is constantly evolving to be invulnerable to the different methods of harm inflicted upon it.
the film ends with batman having superman fly doomsday beyond his limits into space to try to launch him away from earth but as he struggles to maintain control of the fight alone on the edge of space, the president calls his science advisor, who happens to be Lex Luthor, for what plan of action they should take. Lex convinces him to launch multiple kryptonite tipped nuclear weapons at superman and doomsday. The end result is the final destruction of Doomsday and Superman as collateral damage, who falls back to earth, the fight and explosions resulting in the death of Superman.
