The stalker was incredibly lucky: he got a rare and valuable artifact "Heart" in the Zone. His younger brother, nicknamed Nimble, was even more lucky — he got a tip on a larger target. There is no time to plan a sortie. Without waiting for his brother's consent, Nimble goes to the goal alone. To save his wayward brother, the Stalker is forced to return to the Zone, where his new artifact begins to show unexpected properties. Breaking through military cordons, gangs of looters and mutants, the Stalker encounters something more dangerous than anything he has seen before.