On July 23, 1998, special tactics force Bravo Team is sent to the suburbs of Raccoon City, with the mission of investigating a series of unusual murders. Eventually, the media finds out about the killings and they start to divulge it to the populace. The reports indicate that whole families are being victimized by crazed individuals. On that night, contact with Bravo Team is completely lost.

On July 24 1998 and a few hours later, another unit of the S.T.A.R.S. force makes it's way to Raccoon Forest. Where they find the crash site of the missing team's helicopter. Inside the chopper, they find the body of one of the pilots. However, there is no sign of the other members whereabouts. Alpha Team's leader and commander, Albert Wesker, orders his team to begin searching the area for any survivors. The order is followed by every member of Alpha Team. Except for pilot Brad Vickers, who remains inside the helicopter. The officers on the ground are: Chris Redfield; Jill Valentine; Barry Burton and Joseph Frost.

Suddenly, the team is attacked by a blood thirsty pack of dogs. Wesker guides the bewildered officers to find refuge inside a solitary Mansion in the middle of the forest.

Once inside the Mansion, Wesker commands his subordinates to begin searching the premises for clues. Jill Valentine and Barry Burton separate from each other during their exploration of the mansion. But they try to keep close tabs on each other. Chris Redfield goes solo for a while, until he comes face to face with a couple of surviving members of Bravo Team.

He finds Rebecca Chambers and Richard Aiken. Unfortunately, Richard is badly wounded and has need for a special serum. They take Richard to a safe spot and Rebecca stays with him while Chris continues to explore the creepy estate. Rebecca later joins him to help with some mystery solving.

Things don't get better for them, as they soon discover that the mansion and surrounding areas are populated by zombies. They were apparently old residents and employees who had suffered the effects of a terrible outbreak of a synthetic virus. The virus, known as T-Virus, was responsible for the deaths that Bravo Team had been sent to investigate.

Chris and Jill find documents that reveal details about the mansion. The place was used as a research center for the development of Bio-Organic Weapons (B.O.W.) using animals and even humans. Rebecca had previously come in contact with similar creatures. But after the death of Richard Aiken, she begins to break apart emotionally. She manages to hold herself together with the support of Chris, who reminds her of her duty. He instructs her to perform certain objectives, in order to keep her mind busy at all times. Meanwhile, Jill Valentine discovers a shack outside the mansion. There she finds a tormented creature, that seems to be a horrendous experiment gone wrong. The creature is tied somehow to the mansion and the corporation that build it, Umbrella Corp.

In and around the mansion, the S.T.A.R.S. members have to make battle against horrible creatures. One more fearsome than the other. It seems that the creatures appear out of nowhere. And yet, it's like they're being expose to them. But by whom?

The surviving team members of Alpha and Bravo team, suspect that there is a dark conspiracy against them.