U.S. federal agent Leon S. Kennedy sneaks into the "East Slavic Republic" to verify rumors that Bio-Organic Weapons (BOWs) are being used in the country's civil war, which the U.S. and Russia are making preparations to jointly intervene in. Right after his infiltration, the U.S. government orders him to leave immediately. Determined to uncover the truth, Leon ignores the order and enters the battlefield to end the chain of tragedies caused by the BOWs.

When a virus leaks from a top-secret facility, turning all resident researchers into ravenous zombies and their lab animals into mutated hounds from hell, the government sends in an elite military task force to contain the outbreak.