In Batman: Year One, Bruce Wayne returns to Gotham City after spending years abroad training in martial arts, forensics, and detective work in order to fight crime as a vigilante. He is aided by his loyal butler Alfred, who provides him with equipment and support.
Jim Gordon, on the other hand, transfers to Gotham City from Chicago, hoping to start a new life with his pregnant wife Barbara. However, he quickly realizes that corruption within the police department is rampant, and he refuses to be a part of it. He forms an uneasy alliance with another honest cop, Sarah Essen, but they are both targeted by the corrupt officers.
As Batman begins to make his presence known, Gordon is assigned to catch him. However, as Gordon begins to understand the true nature of the vigilante's work and witnesses his success, the two men forge a bond of mutual respect. Together, they work to take down the corrupt police officers, as well as other villains such as Carmine Falcone and Catwoman.
Throughout the film, Batman struggles to balance his desire for justice with his own personal demons. He is haunted by the memory of his parents' murder and struggles with feelings of guilt and isolation. Meanwhile, Gordon faces personal struggles of his own, including infidelity and estrangement from his wife.
In the end, Batman and Gordon's partnership proves successful, and they emerge as heroes in the eyes of the citizens of Gotham City. The film ends with the suggestion that they will continue to fight crime together, as allies in the war against corruption and injustice.