The novel opens with its chief protagonist, Kris Kelvin, heading towards the Prometheus, a space station floating above the mysterious Solaris. His mission is to observe the planet and its seemingly sentient blue ocean in an activity known as Solaristics, which has been going on for some time to little or no effect: in fact one crew member, Gibarian, had committed suicide after losing his mind; a second, Sartorius, has locked himself away; the third, the haggard and rambling Snow, is the only one willing to talk.

Snow warns Kelvin about strange goings-on involving visits from mysterious beings. Kelvin first encounters a black woman stalking the corridors, but things get truly weird when he is visited by his dead wife, Rheya. The reader learns their relationship ended several years before and she killed herself as a result. Kelvin has since been wracked by guilt and this is seized upon by the intelligent ocean below.

Although the ocean has been studied for years, humankind has got no closer to understanding it, although they know it is capable of independent movement and thought - thoughts so powerful it can infiltrate the minds of nearby life. By doing so, the ocean creates avatars that represent its targets' most painful and repressed memories.

The more the crew bombard the ocean with X-rays, the more it responds in anger.

In many ways the novel is a meditation on pain and guilt, but also the arrogance of mankind in exploring other worlds and other species to conquer.

was made into a mesmerising 1972 movie by Russian filmmaker Andrei Tarkovsky, and a 2002 version by Steven Soderbergh.