Bruce Wayne saw his parents killed and the corrupt take over Gotham. He leaves to explore the criminal underworld, to better understand the criminal mind, and how to defeat it.
While locked in an Asian prison, a man named Ducard talks to him. He brings word from Ra's al Ghul, offering to train Bruce. Ra's runs the League of Shadows, a group dedicated to fighting evil. Bruce has to prove himself before he can join and learn how to fight. He has to pick a rare blue flower and climb to the top of a mountain to give it to Ra's. He does so and begins his training.
Bruce is afraid of bats and he blames himself for his parent's death. He needs to learn how to face and conquer his fears, and control his overpowering rage. He learns how to fight, to disappear in plain sight, to use explosive powders as a distraction, and much more.
He is given a chance to join the League, but he must prove himself a final time. He is supposed to lead the League to Gotham, to destroy Gotham. He is expected to kill a criminal, as a final proof of his loyalty. He refuses and burns the League's base down. He returns to Gotham.
He goes to his father's company. He wants to learn the company from the bottom up. He asks to start at Applied Sciences Department. This is run by Lucius Fox. He starts borrowing the toys that were abandoned as unprofitable. He plans on using them in his new profession as a crimefighter. We get to see the beginnings of all the toys we've come to associate with the Batman mythos.
Falcone is the crimelord everyone looks to as the power. On Falcone's last drug shipment, Batman makes his first official appearance. He leaves Falcone strapped to a spotlight.
While investigating where the drugs are going to, he gets a full blast of fear gas courtesy of the Scarecrow. It's a powerful hallucinogen. Alfred calls Fox, who analyzes his blood and makes an antidote. Bruce tells him he needs more and Fox gets to work on it.
Dr. Crane, aka Scarecrow, gasses Rachel Dawes (assistant DA) when she insists on Falcone getting checked by her choice of doctors. Batman saves her and finds out that Ra's al Ghul is behind the Scarecrow and Falcone. Batman tells Gordon that Crane's been smuggling his panic-inducing toxin in by hiding it inside Falcone's drugs and dumping it in the water supply. Ra's plans on watching the city tear itself apart while lost in fear.