U. S. S.
U.S.S. Delta Team (also known as "Wolfpack") enters the Raccoon City Underground Laboratory, where they meet up with U.S.S. Alpha Team leader HUNK. Their mission: to assist the Alphas in stopping Dr. William 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 that Birkin has paid-off numerous U.B.C.S. mercenaries into working for him while the deal goes forward. When they reach Birkin's lab, the doctor is shot at from behind a closed door, HUNK and another Alpha leave with the samples. Heading up the elevator to meet up with GOBLIN 6, they soon find that Birkin has survived the attack and injected himself with the virus. The 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 city-wide, and people are beginning to turn into zombies soon after. In what they see as a punishment by U.S.S. 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 U.B.C.S. mercenary, Nicholai Ginovaef and montior him. However, he is soon revealed as a traitor and attempts to kill the Wolfpack.
Later, the team is sent out around Raccoon Park to find the Nemesis, 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 all done, the team exits the station, and soon after encounter rookie R.P.D. Officer Leon S. Kennedy, whom they begin to hunt down.
The Wolfpack chase Leon through a dozen streets despite his pleas to stop shooting at him. U.S.S command grow anxious and abandon Wolfpack in favor of Plan B (The deployment of several T-103s and Hunters from drop pods). Eventually, after a lot of fighting, Leon successfully evades the squad and they decide to find shelter for a breather.
They mop up a small Spec Ops force at a barricade outside City Hall, as well as a pack of Hunters. The Wolfpack then find themselves ambushed by two T-103s and barely manage to take them down. The team retreats into an abandoned Barber shop to catch their breath, making failed attempts to get back in touch with U.S.S command.
Shortly after that, Wolfpack are making a last stand and take down just over 1000 B.O.W.s attacking their position, Umbrella command decides to give the team one final chance and order them to return to Birkin's lab to find Leon. The team find themselves back at square one and eliminate countless enemies as they make their way through the labs.
They engage in battle with Ada Wong briefly before she makes her escape. The self-destruct sequence activates and the Wolfpack see Leon kiss Ada and her supposed death on the control room's camera monitor. Wolfpack then fight their way to the power room to find Leon and Ada missing. With little choice left, they abandon the facility but not without fighting the Super Tyrant which emerged from the boiler earlier on.
Eventually, U.S.S. Command finds the location of Leon, who are also with Claire and Sherry, and sends Wolfpack over to Lonsdale Yard where they have teamed up with whatever is left of the Army Spec Ops to defend the train yard. The Wolfpack break through their lines despite Claire's attempts at decimating them with a grenade launcher as well as massive mobs of Crimson Heads and zombies.
With Claire going into retreat, Leon comes out of hiding with a sniper rifle firing at the Wolfpack. The Wolfpack then fire upon the spec ops guarding Leon's platform and cause a soldier to bleed heavily causing a blood frenzy amongst the B.O.W.s. They smash down the barricade and overwhelm the last of the Spec Ops.
Wolfpack make their way to the ladder and subdue Leon using him as bait to lure Sherry and Claire out of hiding. Leon questions what they fight for and the Wolfpack engage each other 2 on 2. The defenders of Leon believing they can use him as leverage for evac, whilst the assassins believe carrying out these orders will finally earn them evac as well.
The player character and one other member of Delta Team are forced to kill their former comrades, who argue that Leon S. Kennedy must die in order for the mission to be completed. Afterward, they capture a wounded Kennedy, along with Claire Redfield and Sherry Birkin. However, they disregard U.S.S. Command's instructions to immediately execute the R.P.D. officer, hoping to use their hostages as leverage for negotiation. Command is outraged by Wolfpack's defiance and refuses to make a deal with traitors, thus causing the former U.S.S. operatives to sever their allegiance to Umbrella.
With no further use of Kennedy and his companions, Wolfpack allows them to live, partly to spite Umbrella as well. As they move to depart from the ruins of Raccoon City, Wolfpack vows to destroy the Umbrella Corporation from within.
In the alternate ending of the U.S.S. campaign, the player character and one other member of Delta Team remain faithful to the Umbrella Corporation, although two other operatives betray the company by protecting Leon S. Kennedy. After executing the traitors and Leon, the surviving members of Wolfpack capture Claire Redfield and Sherry Birkin. Contacting U.S.S. Command to report the successful completion of their objective, Wolfpack is instructed to kill Claire and deliver Sherry to Umbrella. Claire pleads for mercy, but the player character simply states that they are following orders, shortly before shooting her in the head.