The Flash
After helping Bruce Wayne / Batman and Diana Prince / Wonder Woman stop a robbery in Gotham City, Barry Allen / The Flash revisits his childhood home, where he lived with his parents Nora and Henry, before Henry's wrongful imprisonment for Nora's murder.[a] On the day of her death, Nora sent Henry to the grocery store for some canned food she forgot to buy, leaving her alone in the kitchen where she was killed by an unidentified assailant.[b] Overcome by emotions, Barry accidentally uses the Speed Force to form a Chronobowl and travels back in time to earlier that day. Despite Bruce's warnings of time travel's unintended consequences, Barry places the can in Nora's grocery cart to prevent Henry from leaving the house. As he returns to the present, Barry is knocked out of the Chronobowl by an unknown speedster and arrives in an alternative 2013 where Nora is alive. He encounters his parents and his past self, and realizes this is the day he originally obtained his powers.
To ensure his past self gains superpowers, the two Barrys go to the Central City Police Department, where Barry reenacts the event for 2013-Barry to be struck by lightning. Both end up getting struck by the lightning, giving 2013-Barry powers, but causing Barry to lose his own. As Barry struggles to train his younger self on properly using his powers, they learn that General Zod is preparing to invade Earth.[c] To fight Zod, the Barrys attempt to assemble the Justice League but are unsuccessful; in this timeline, Diana cannot be located, Victor Stone has not gained his abilities yet, and Arthur Curry never existed. They travel to Wayne Manor, hoping to find Bruce, but they instead find an alternate version who has long retired. Bruce theorizes that using time travel to alter history affects events both before and after the alteration. They convince Bruce to return as Batman and help them find Kal-El / Superman.
The Barrys and Batman locate a Kryptonian pod discovered in Siberia. Upon arrival, they instead find Kal-El's cousin, Kara Zor-El, imprisoned in the facility. They rescue Kara and return to Wayne Manor. Barry enlists Bruce's help to regain his powers once more. The first two attempts fail, prompting Kara to fly Barry into a storm, where he regains his powers. Kara and Batman join the Barrys to fight Zod and his forces. During the battle, Kara learns that Zod had intercepted Kal-El's escape pod from Krypton and killed him while attempting to extract the Codex needed to repopulate the Kryptonian species. Zod reveals that the Codex is actually within Kara. Zod subdues and kills her, then extracts the Codex from her blood; meanwhile, Batman sacrifices himself in an unsuccessful attempt to destroy Zod's ship.
The Barrys repeatedly time travel to save Batman and Kara but keep failing. Barry realizes this sequence of events cannot be changed, but 2013-Barry keeps trying. As 2013-Barry travels, the multiverse starts to implode. The unknown speedster who initially knocked Barry out of the Speed Force returns and is revealed to be an older, future version of 2013-Barry who still believes he can defeat Zod and save his Earth. He becomes angry when Barry reveals his intention to reverse the changes he made to the timeline by letting Nora die. The elder 2013-Barry attempts to kill Barry, but instead impales young 2013-Barry, who sacrifices himself to save Barry and wipe his future self from the timeline. Barry reverts the timeline and comes to terms with his mother's death; however, he subtly alters the past by moving the canned food to a higher shelf. Returning to the present day, Barry attends Henry's court hearing, where the security footage now reveals Henry looking up to grab the can, allowing for his exoneration. Barry is then contacted by Bruce, whose appearance has changed once again due to the timeline alteration.
