Major Konstantin Kupriyanov, a special operative-intruder of the military intelligence agency, entered the Zone not for the sake of searching for artifacts and thrills. Fulfilling orders from the command, he follows the trail of the stolen Purga-D missile system, transported across the perimeter of the Zone by a gang of smugglers in uniform. The major's task is to prevent the newest weapon from falling into the hands of the paramilitary sect "Monolith", which intends to use it to destroy the Heavenly Spider - a mysterious impregnable citadel. While planning the operation, Kupriyanov has no idea what an insidious trap his raid on the Zone will lead into, which intends to pit the intruder against the most cruel enemy - his own bloody past...