Leaked plot details

Barbara Gordon (Leslie Grace) returns to Gotham City after attending college and reunites with her father, Commissioner James Gordon (J.K. Simmons).
Barbara attempts to join the Gotham City Police Department against Gordon’s wishes, but ends up in a desk job as a computer analyst.
Barbara admires Batman, who has disappeared, and the new generation of vigilantes he has inspired, particularly the Black Canary (Jurnee Smollet).
Barbara trained martial arts in college. She begins to engage in vigilantism, aided by her transgender friend Alysia Yeoh.
Barbara investigates a series of fires and learns that the culprit is vengeful firefighter turned arsonist Garfield “Firefly” Lynns (Brendan Fraser).
Meanwhile, Gordon joins forces with District Attorney Janice Porter to take down mobster Carmine Falcone.
Their case relies on the testimony of Falcone’s former enforcer Mickey Sullivan, so Falcone hires Firefly to eliminate them.
At the same time, Barbara develops a relationship with Alberto Romano (Jacob Scipio), unaware that he is Falcone’s estranged son.
Barbara foils Firefly’s attack on Porter in a makeshift batsuit but fails to save Sullivan, attracting the attention of Bruce Wayne (Michael Keaton).
Wayne recruits Barbara through the Black Canary, who trains her, while Bruce provides her with a new suit and arsenal.
Barbara finds out about Alberto and urges him to stand against his father, but he is reluctant, straining their relationship.
Firefly kidnaps Gordon for Falcone. Barbara confronts them, saves her father, defeats Firefly and arrests Falcone.
Alberto ultimately testifies against Falcone, who is convicted, but he must then leave Gotham for the FBI's Witness Protection Program.
Bruce reveals to Barbara that he was once Batman and chooses her as his successor, Batgirl.
Meanwhile, Black Canary is assigned by Bruce to investigate activity by the League of Assassins in Gotham, setting up her spinoff film.