Captain Trips is a nickname for the constantly shifting antigen virus (originally known as the Blue Virus) that exterminates 99.4% of the human population in Stephen King's The Stand. Developed under the codename Project Blue by a biological weapon's laboratory located beneath California's Mojave Desert, it is also known as A-Prime, A6, Rales, Superflu, and Tube Neck. The only three people who are aware of the virus are the homeless doomsayer known as the Monster Shouter, the benevolent old woman Mother Abagial, and the demonic wizard Randall Flagg.