The U.B.C.S. Commandos, led by Klaus, are sent into Raccoon City to secure a scientist by the name of Dr. Cameron. After coming across her ID card, they use a tracking device to located her. At there first stop (a warehouse) they encounter a B.O.W. that takes out Roberto. The team kills the B.O.W., but its DNA lives. A cockroach feasts on a piece of the destroyed body and now becomes a carrier. The cockroach sneaks up on the squad and listens to the convo. between one another. After the squad heads out, the cockroach infects a rat, which then infects an injured crow.

The team stops at a manhole where the scientists signal is now strongest. Norman and Roger go along with Klaus into the sewers. Their other team member, Ed, is stationed by the Hummer to guard the area. They only find the doctor's equipment and a Cerberus waiting to feast. While they are down in the sewers, Ed faces off against the infected crow. Ed is killed by the crow. As the other two men climb to the streets and investigate the area, Norman is killed. The B.O.W. is now hosting in a human body... and begins to chase Klaus.

Being cased thru the sewers, Klaus finds an open manhole which the B.O.W. can not fit thru. This gives Klaus time to kill the zombies on the streets. Once the B.O.W. breaks thru the grounds and meets Klaus on the streets, he stabs Klaus in the heel with one of its tentacles. The other remaining member of the Commandos, Roger, helps Klaus get back into the truck. They speed off, destroying the B.O.W. with the mounted Machine Gun in the back of the Hummer

After a short nap Klaus awakes and thanks Roger for saving his life... Roger is silent. Klaus starts to asks questions regarding the virus. Roger explains how it moves from life form to life form... making it almost impossible to kill. A cockroach crawls into Roger's ear and a tentacle bursts from his chest. Roger turns towards Klaus and now has the face of Dr. Cameron's attached to his. The new B.O.W. (which appears to be the Doctor) explains that she realized Umbrella was after her research. She then tells Klaus how the U.B.C.S. Commandos made perfect 'guinea pigs' for her virus.

She explains to Klaus that she will be able to always look normal and get away from Umbrella. She tells him that Umbrella will never be able to get her research. Klaus is then finished as her tentacles pull his face apart into pieces.