In the future - the “cosmic future” of mankind, very far from us - these farewell words will be heard: “Kelvin, you are flying. Good luck!" Psychologist Kelvin, at an incredible distance from Earth, is landing from a spaceship to a planetary station - this is a huge silver whale hovering above the surface of the planet Solaris. The station seems empty, it is strangely littered, no one meets Kelvin, and the first person who sees a psychologist is scared almost to death. The man’s name is Snout, he is the deputy chief of the station of Gibaryan. He wheezes in disgust: “I do not know you, I do not know. What do you want?" - although the station was notified of the arrival of Kelvin. And then, recollecting himself, he says that Gibaryan, a friend and colleague of Kelvin, committed suicide and that the newcomer should not do anything and should not attack if he sees someone else except him, Snout, and the third crew member, physicist Sartorius. To the question: “Who can I see ?!” - Snout, in fact, does not respond. And very soon, Kelvin meets a huge naked black woman in the corridor, a “monstrous Aphrodite” with huge breasts and an elephant's backside. She can't be at the station, it's like a hallucination. Not only that, when a newcomer arrives at Sartorius, the physicist does not let him into his cabin - he stands, blocking the door with his back, and there you can hear the running around and the laughter of the child, then the door starts to twitch, and Sartorius shouts in a frantic falsetto: “I'll be right back! Do not! Do not!" And the culmination of delirium - Kelvin enters the refrigerator to see Gibaryan’s body, and discovers the same black woman, alive and warm, next to the dead man, despite the icy cold. Another striking detail: her bare feet are not erased and not deformed by walking, their skin is thin, like that of a baby.

Kelvin decided that he had lost his mind, but he is a psychologist and knows how to make sure of this. He arranges for himself a check and summarizes: “I have not lost my mind. Last hope has disappeared. "

At night, he wakes up and sees next to him, his wife, who died ten years ago, who killed herself because of him, Kelvin. I live, in flesh and blood, and completely calm - as if they broke up yesterday. She is wearing a dress commemorating him, an ordinary dress, but for some reason without a zipper on her back, and her feet, like that of a black woman, are infantile. It seems that she takes everything for granted and is happy with everything, and wants only one thing: not for an hour, not a minute to part with Kelvin. But he needs to leave in order to somehow understand the situation. He tries to tie Harie - it turns out that she is not strong humanly ... Kelvin is horrified. He lures his wife's phantom into a single rocket and sends him to near-planet orbit. It would seem that this nonsense is over, but Snout warns Kelvin that in two or three hours the “guest” will return, and finally tells what, in his opinion, is happening. Persistent "guests" sends to the people of the Ocean planet Solaris.

This ocean has been occupying the minds of scientists for more than a hundred years. It does not consist of water, but of protoplasm, moving in a strange and monstrous way, expanding and creating gigantic - meaningless-looking - structures, in the depths of which time changes its course. They were dubbed “goroderov,” “dolguns,” “my moids,” “symmetries,” but no one knew why and why they were created. This living Ocean seems to have one function: it maintains the optimal planetary orbit around the double Sun. And now, after a research hit by hard radiation, he began to send phantoms to people, extracting their appearance from the depths of the human subconscious. Kelvin was still lucky: he was “presented” with a woman whom he had once loved, while others were sent their secret erotic desires, which were not even realized. “Such situations ...” says Snout, “of which you can only think, and even in a moment of intoxication, fall, madness ... And the word becomes flesh.” So says Snout. He also says that the “guest” most often appears while a person is sleeping and his consciousness is turned off. At this time, the brain regions responsible for memory are more accessible to the unknown rays of the Ocean.

Scientists might leave the station, but Kelvin wants to stay. He thinks: “Perhaps we don’t know anything about the Ocean, but maybe about ourselves ...” The next night, Harry appears again, and, like in the old days, they become lovers. In the morning, Kelvin sees that in the cabin there are two “absolutely identical white dresses with red buttons” - both cut at the seam. Another shock follows this shock: Hary accidentally remains locked up and with inhuman force, wounding herself, breaking down the door. Shocked Kelvin sees her mutilated hands heal almost instantly. Hary herself is also terrified, because she feels herself an ordinary, normal person ...

Trying to understand how Harie was "structured", Kelvin takes her blood for analysis, but under an electron microscope it is clear that the red bodies are not composed of atoms, but as if from nothing - apparently, from a neutrino. However, “neutrino molecules” cannot exist outside of any particular field ... The physicist Sartorius accepts this hypothesis and undertakes to build an annihilator of neutrino molecules to destroy the “guests”. But Kelvin, it turns out, does not want this. He has already recovered from the shock and loves his newfound wife - whoever she is. For her part, Harry begins to understand the situation, all its tragedy. At night, while Kelvin is sleeping, she turns on the tape recorder left by Gibaryan for Kelvin, listens to Gibaryan’s story about the “guests” and, having learned the truth, tries to commit suicide. Drinks liquid oxygen. Kelvin sees her agony, excruciating bloody vomiting, but ... Ocean Radiation restores neutrino flesh in minutes. She came to life in despair - now she knows that she’s tormenting Kelvin, “And that I couldn’t imagine that the instrument of torture could be good and love,” she shouts. Kelvin in response says that he loves her, namely her, and not that earthly woman who killed herself out of love for him. This is true, and he is completely at a loss: after all, he will have to return to Earth, and his beloved woman can exist only here, in the mysterious radiation field of the Ocean, He can not decide on anything, but agrees to Sartorius’s proposal to record the currents of his brain and transmit them in the form of an x-ray beam to the ocean. Maybe, after reading this message, the liquid monster will stop sending its phantoms to people ... The beam hits the plasma, and as if nothing is happening, only Kelvin begins tormenting dreams in which he seems to be studying, then sorting into atoms, then making up again. “The horror experienced in them cannot be compared with anything in the world,” he says. This goes on for several weeks, Harie and Kelvin become attached to each other more and more, and Sartorius, meanwhile, conducts some terrible experiments, trying to get rid of the "guests". Snout says about him: "Our Faust, on the contrary, is looking for a cure for immortality." Finally, one night, Harry gives Kelvin sleeping pills and disappears. Sartorius, secretly from Kelvin, nevertheless created a phantom annihilator, and, out of great love for Kelvin, she decided to die - as once, a long time ago ... She went into oblivion, left forever, for the invasion of the "guests" was over.

Kelvin in grief. He dreams of taking revenge on the thinking protoplasm, burning it to the ground, but Snout manages to calm his comrade. He says that the Ocean did not want anything bad, on the contrary, he strove to give people gifts, to give them the most precious, that which is deepest hidden in his memory. The ocean could not know what the true meaning of this memory ... Kelvin accepts this thought and calms down - as if. And in the last scene, he sits on the shore of the Ocean, sensing his "gigantic presence, powerful, inexorable silence", and forgives him everything: "I did not know anything, but still believed that the time of cruel miracles had not ended."