A story that reveals the whole story of a friendship that has been changed over 20 years based on the death of a friend of Jang Jae-kyeong, an ace detective in a drug squad who is forcibly addicted to drugs.

Professor Se Jeong attends a biotech conference, only to witness it spiral into catastrophe when a rapidly mutating virus is unleashed. As the outbreak spreads and the infected begin to transform, authorities seal off the entire facility.