Roadside Picnic by Arkady and Boris Strugatsky
Red Schuhart is a stalker, one of those young rebels who are compelled, in spite of extreme danger, to venture illegally into the Zone to collect the mysterious artifacts that the alien visitors left scattered around. His life is dominated by the place and the thriving black market in the alien products. But when he and his friend Kirill go into the Zone together to pick up a “full empty,” something goes wrong. And the news he gets from his girlfriend upon his return makes it inevitable that he’ll keep going back to the Zone, again and again, until he finds the answer to all his problems.