BSAA agent Chris Redfield is tracking down a notorious arms dealer who is looking to sell a deadly virus. During his mission, Chris stumbles upon a clue that leads to the discovery of a new bio-organic weapon. His investigation takes him to a mansion where he finds a group of researchers taken hostage and turned into zombie-like creatures as a result of the new virus. Determined to stop the spread of the infection, Chris teams up with Rebecca Chambers, a professor and former member of the STARS division, who has developed a vaccine for the virus. However, their efforts take a turn when the arms dealer's monstrous plan begins to unravel, revealing a deeper conspiracy that threatens to unleash a global catastrophe.

Rebecca is captured by the arms dealer, Glenn Arias, a man with a vendetta against the governments he holds responsible for the death of his friends and family. Meanwhile, Leon S. Kennedy, a skilled government agent haunted by memories of past incidents involving similar bio-organic weapons, is reluctantly pulled into the conflict. Leon, battling his personal demons, must join forces with Chris and Rebecca, combining their expertise to track down Arias before he can execute his plan. As time runs short, the unlikely team confronts the enhanced horrors created by the virus and uncovers Arias's intricate and deadly scheme, leading to a race against the clock to prevent a catastrophe of epic proportions.