The plot revolves around a member of a special ops team headed by the returning main character from Shellshock: Nam '67, Caleb "Cal" Walker, that vanished after being sent into the jungles of Cambodia to retrieve cargo known as WhiteKnight which was lost after U.S. transport plane carrying it was shot down by an NVAF jet. Whiteknight is the codename for a French military biological weapons expert named Pierre DuMont and his virus that were onboard the plane. Cal lost his men to the earliest victims of Whiteknight, the downed U.S. Plane crews. Cal was infected with the very virus that he meant to secure. One month after the event, Cal came out from the jungle alone, only to be captured and brought to a U.S. base in the Pleiku Highlands. Cal's newly drafted brother, Pvt. Nathaniel "Nate" Walker was brought by Sgt. Jack Griffin to the base in order to extract info regarding Whiteknight from his insane and enraged brother. Unfortunately, Cal was able to escape after killing some Marines during a VC Special Ops assault on the building Cal was being kept in. The attack was orchestrated by Nguyen Van Trang, a scarred VC Special Ops officer to capture Cal. Nate, with help of Sergeant Griffin, and also friendly GIs that he met along the way, must hunt down Cal through the town of Pleiku and various other locations. Finally, he reaches an old temple in Laos. Nate is also tasked with stopping Van Trang and his cohorts from capturing Cal and Whiteknight. Not only fighting infected victims of Whiteknight, he also has to fight joint VC/NVA forces, stop the infection from breaking the quarantine zone, and solve the Whiteknight mystery for good.