A mysterious explosion destroys the Chernolton research facility near Moscow. Lucifer Alpha, a powerful biological weapon under secret development there, is released into the atmosphere, creating a deadly biohazard. Carried by the trade winds, Lucifer Alpha spreads throughout Eastern Europe and Eurasia, destroying 80% of the populace. Half of the world's people die. The greatest biohazard in history later becomes known simply as "The Catastrophe". But at this time, who could have possibly imagined that the ultimate biohazard wouldn't occur for another half century?
50 years later, mankind faces its greatest crisis, the appearance of a mysterious android lifeform. Its purpose and origin are unknown. Is it a new form of weapon? Or perhaps, an invasion from some other world? They appear during winter killing humans, and infiltrating society by taking the place of their victims. Employing an artificial skin, they can sweat and even bleed. Part organic, part machine, they're almost impossible to distinguish from those they kill. As they steal their victims' bodies in order to take their place, these mysterious invaders become known as "Snatchers".