(Operation Raccoon City's backstory)
Umbrella Security Service (USS) Delta team enters the Raccoon City Underground Laboratory, where they meet up with Alpha team leader HUNK. Their mission is to assist Alpha team in stopping Dr. Birkin from handing over his G-Virus research to the U.S. military and retrieve the G-virus. On their way to Birkin's lab, they find Birkin has paid numerous Umbrella Biohazard Countermeasure Service (UBCS) mercenaries to work for him while the deal goes forward. When they reach Birkin's lab, the doctor is shot, and HUNK and another Alpha leave with the samples. They soon find that Birkin survived the attack and infected himself with the virus. The Birkin creature proceeds to kill off most of Alpha team before disappearing; HUNK offers to go back in search of the sample.
Not long after the battle, it becomes evident that the T-virus has leaked citywide, and people are beginning to transform into flesh-hungry zombies. In what they see as a punishment by USS command, Delta team is ordered to remove evidence of Umbrella's role in the outbreak. Heading into Raccoon City Hall, Delta team meets with a UBCS mercenary and they monitor Nikolai Zinoviev; he is soon revealed as a traitor and attempts to kill Delta team.
Later, the team is sent out around Raccoon Park to find the Nemesis-T Type, which has gone rogue. A second parasite is injected into its body in order to bring it back under control. Shortly after this mission is completed, the team is then sent out to the Raccoon City Police Department, ordered to kill any surviving police officers and destroy evidence linking the company to the outbreak. When this is done, the team exits the station, and soon after encounter Leon S. Kennedy, whom they begin to hunt down along with Sherry Birkin. After they find and corner Leon, Claire Redfield and Sherry, the game can end in two ways: in one ending, the team resigns from Umbrella over their abandonment during the mission and betrays them by letting the three live; in the other, Leon and Claire are executed and Sherry is sent to an Umbrella facility.