In an alternate history, a second mysterious disaster strikes the area around the Chernobyl Nuclear Power Plant years after the original 1986 accident, leaving behind a lethal territory called the Zone that is populated by mutated creatures, deadly anomalies, and scavengers known as stalkers. The player takes the role of the Marked One, a man who survives a crash with no memory of his past. His only clues are a tattoo reading S.T.A.L.K.E.R. and a handheld device carrying a single instruction: kill a man named Strelok. Working for a local trader to repay a debt, the Marked One follows this trail deeper into the Zone, gradually uncovering hints about Strelok and the secrets hidden at its heart.