Rookie police officer Leon drives into Raccoon City ready for his first day, soon discovering it besieged by zombies. Joining fellow survivor Claire Redfield, the two drive in a police car to the Raccoon Police Station in the hopes of finding help. Attacked by a zombie from the back seat, they swerve 180 degrees and collide with the back of the station, killing the zombie. A truck then crashes into the car, separating Leon and Claire on different ends of the road.
Leon makes his way into Kendo Gun Shop, where he meets the shopkeeper, who warns him that the entire town is infested, before being eviscerated by zombies that break in. Leon flees, and later enters the Raccoon Police Station through its front door and is introduced to his superior, Marvin Branagh, who warns him that the Zombie-related killings have been going on for months, but were ignored completely, until two months earlier, after the S.T.A.R.S. team was discredited.
Ada gets the Club Key via the vent. Ben and Chief Irons are implanted by Birkin. Leon fights the G-creature and Claire confronts Birkin. After Ada chases her to the sewage maintenance area, Annette ambushes her and tells her about the G-Virus, the attempted murder of her husband, and how the city had been infected. Annette tries to shoot her, but Ada, with her quick and agile skills, manages to overthrow Annette, who falls down into the sewer. Leon is confronted by Annette and learns from her that Ada was a spy. Annette has a sample of the G-Virus, which will be acquired by Leon due to her being knocked out cold by a falling large pipe after a sudden, strong quake. Ada tells Leon to hand her over the G-Virus, or she'll shoot him. However, Leon doesn't know that there are no bullets in the gun's magazine. However, Ada would force him to give her the sample. Ada is then shot from behind by Annette and falls down the chasm. Out of despair and grief, Leon threw the G-Virus sample away. He must then defeat the mutant Birkin in one of his final forms, then escape by getting on the train.