After th events of 2023's The Flash, Barry Allen returns to his timeline, relieved by his father's innocence and the Justice League’s restoration, a twist awaits. An unnamed driver, played by George Clooney, opens the door for Bruce Wayne, revealing another alternate timeline. In this world, Supergirl is alive, dearly missed by Barry, Barry's mother's murderer is unmasked as Professor Eobard Thawne, a 25th-century curator of the Flash Museum turned vengeful speedster. Thawne's obsession with Barry spiraled after the museum's replicas were deemed terrible, leading to the loss of his money and the death of his mother. His vendetta? Making Barry suffer the same heart-wrenching loss. With the Reverse-Flash now a menacing threat, Barry teams up with this timeline's Batman and Supergirl. Along the way, they gain an ally in Green Arrow, who harbors a crush on singer Dinah Lance, The stage is set for an epic battle against the Reverse-Flash setting in Las Vegas in the rest of the movie, with Barry determined to protect the ones he loves and restore peace across timelines.
