The game kicks off with Chris and Sheva on a mission to investigate a possible bioterrorism threat in Kijuju, a fictional African city. Their investigation quickly uncovers a sinister plot by a mysterious organization, Uroboros, to spread a new, highly potent bioterrorism agent known as Uroboros virus. The duo soon finds themselves entangled in a web of conspiracies and facing hordes of the infected, alongside more terrifying foes.