Stalker is a 1979 art film directed by Andrei Tarkovsky, with its screenplay written by Boris and Arkady Strugatsky. Loosely based on the novel The Roadside Picnic, the film features a mixture of elements from the science fiction genre with dramatic philosophical and psychological themes. It depicts an expedition led by a figure known as the 'Stalker' (Aleksandr Kaidanovsky) to take his two clients, a melancholic writer (Anatoli Solonitsyn) seeking inspiration and a professor (Nikolai Grinko) seeking scientific discovery, to a site known simply as the 'Zone', which has a place within it with the supposed ability to fulfill a person's innermost desires. The trio travels through unnerving areas filled with the debris of modern society while undergoing many arguments, facing the fact that the 'Zone' itself appears sentient while their path through it can be sensed but not seen. In the film, a stalker is a professional guide to the Zone, someone having the ability and desire to cross the border into the dangerous and forbidden place with a specific goal.