Years later, Bruce returns to Gotham City from Princeton University, intent on killing Chill, whose prison sentence is being suspended in exchange for testifying against crime boss Carmine Falcone. Before he can act, however, one of Falcone's female assassins posing as a reporter kills Chill. Rachel Dawes, Bruce's childhood friend and now an assistant district attorney, is disgusted with Bruce's intent, telling him his father would be ashamed of him. That night, Bruce confronts Falcone, who tells the young man that his criminal empire is invincible because it runs on fear. Inspired, Bruce decides to travel the world for several years, learning the various ways of the criminal underworld, before himself becoming a criminal and being arrested. After Bruce's training in the League of Shadows, Ra's and Ducard tell Bruce his purpose: He must lead the League to destroy Gotham, which they believe is corrupt beyond saving. Bruce refuses to become a murderer and battles Ra's, burning the temple in the process, before making his escape. Ra's is killed by falling debris, but Bruce saves an unconscious Ducard and returns to Gotham.
Falcone now dominates the city. Bruce enlists the help of Sgt. Jim Gordon, one of the city's few honest police officers, and befriends Lucius Fox, a former board member of Wayne Enterprises. Fox helps Bruce acquire a prototype armored car and an experimental armored suit. With Alfred, Bruce finds another entrance to the cave under the well and creates a workshop, modifying his equipment to take up the identity of Batman. On his first night out as a vigilante, he intercepts a drug shipment, captures Falcone and provides Rachel with the evidence to indict him. Falcone and his men are transferred to Arkham Asylum with the help of the hospital's corrupt administrator, Dr. Jonathan Crane, who has been paying off Falcone to ship a toxic hallucinogenic into Gotham City; Crane uses the toxin in his experiments, using his patients as guinea pigs. When Falcone demands a bigger share, Crane gasses Falcone with the same toxin, literally driving him insane with fear. While investigating the drugs, Batman encounters Crane, who also sprays him with the fear toxin. Alfred rescues him, using an anti-toxin developed by Fox. Crane later summons Rachel to Arkham and shows her that the toxin has been introduced into Gotham's water supply from Arkham for weeks, and then infects her. Batman doses Crane with the toxin, saves Rachel, and then takes her to his cave giving her two vials for Gordon: One for inoculating himself and the other for mass production.
At Bruce's birthday celebration at Wayne Manor, he is confronted by Ducard, who reveals himself to be the real Ra's al Ghul, and has now arrived in Gotham personally to destroy the city; he had conspired with Crane to poison Gotham's water supply with the toxin, vaporizing it with a stolen device from Wayne Enterprises. After Bruce pretends to be drunk to get everyone to leave, he and Ra's fight. Ra's' men burn down the mansion, release all the inmates at Arkham, and vaporize the hallucinogen into the atmosphere. Although Wayne Manor is destroyed, Bruce escapes the inferno with help from Alfred. Rachel delivers the antidote to Gordon and wards off Crane, now calling himself Scarecrow, with a taser. Batman reveals his identity to Rachel and then has Gordon drive the Batmobile to Wayne Tower, the central hub of the Gotham elevated rail system. Ra's boards the train; his objective is to reach Wayne Tower with the vaporizer as it is also a major water hub. As Batman confronts Ra's on the train, Gordon destroys the elevated tracks. Batman escapes the train as it crashes, leaving Ra's to die.
Following the battle, Batman becomes a public hero and Bruce gains control of his company; he fires the former CEO, William Earle, and replaces him with Lucius Fox. However, he loses Rachel, who cannot bring herself to love both Bruce and Batman. Gordon, now a Lieutenant, shows Batman the Bat-Signal and mentions a new criminal who leaves Joker playing cards at crime scenes. Batman promises to investigate, and disappears into the night.
source : wikipedia
Batman Begins AVI
