

Lebedev begins to theorize that the Zone is being disrupted by a dramatic increase in energy emissions, emanating from the Chernobyl Nuclear Power Plant in the center of the Zone. Lebedev is amazed that Scar is still alive the Clear Sky lead researcher, Chebekov, believes that Scar has acquired some “unusual ability” that allows him to navigate and survive anomalies and parts of the Zone that would normally kill any ordinary man. Once again Scar is the sole survivor, recovering shortly after the emission dies down. During the rescue attempt another emission occurs with little warning, giving Scar and the Stalkers no time to seek cover. Word arrives that a platoon of Stalkers has come under attack by mutants, and Lebedev, leader of the Clear Sky faction, asks Scar to seek them out and help them. The nature of these changes becomes clear shortly. It is not known how Scar has survived the emission, but it is noted he has suffered damage to his central nervous system and seems to exhibit other, subtle physiological changes. Scar, the only one to survive, is then rescued by Clear Sky, a secret independent Zone faction dedicated to researching and learning about the Zone in their attempt to better understand it and its related phenomena. The player assumes the role of veteran Stalker Scar, who is injured and rendered unconscious by an energy emission while guiding a group of scientists through the Zone. Clear Sky is a prequel to S.T.A.L.K.E.R.: Shadow of Chernobyl.
