The Bioterrorism Security Assessment Alliance, or BSAA for short, is an organization newly formed by the U.S. Government along with the United Nations Security Council and the Global Pharmaceutical Consortium to combat bio hazardous threats around the world that are well above normal dangers. This comes in large part to the B.O.W.s and viral weaponry that had been developed by the former umbrella corporation being sold on the black market to the highest bidder. It has advanced technology and a wide variety of skilled personnel assigned to their duties. It also has a network of Branches across the world, ready to deploy on the first sign of a biohazard.

In West Africa, a city was afflicted by a mutagenic virus, resulting in veteran BSAA operative Chris Redfield investigating the city, and ends up fighting back hordes of mind-controlled villagers. To aid in his efforts to free the region of an unknown person(s) control, Chris teams up with Sheva Alomar, the BSAA's West African Branch operative.