In the future, very distant from us "cosmic future" of humanity – are heard these parting words: "Calvin, you fly! Farewell". Psychologist Kelvin at the incredible distance from the Earth is landing on some preplanetary station – it is a huge silver whale hovering over the surface of the planet Solaris. The station seems to be empty, it is littered with rubbish, nobody meets Kelvin, and the first person who sees the psychologist, is frightened almost to death. This person’s name is Snaut, he is a deputy of the station chief Gibaryan. He wheezes with disgust: "I do not know you, I do not know. What do you want? " although the station has been informed of the arrival of Kelvin. And then, coming to his senses, he says that Gibaryan, a friend and colleague of Kelvin, has committed suicide, and that a newcomer does not have to do anything and does not have to attack if sees someone else except him - Snaut, and the third member of the crew, physics Sartorius. To the question: "Who may I see ?!" Snaut does not respond. And very soon, Kelvin meets in the hallway a huge naked black woman, "monstrous Aphrodite" with huge breasts and ass like an elephant’s. She cannot be at the station, it must have been a hallucination. Moreover, when he comes to Sartorius, the physicist does not let him to his cabin – he stands with his back to the door, and there could be heard a running and laughing child. Then they start to pull the door and Sartorius shouts: "I'll be right back! Do not! Do not". And the culmination of the delirium - Kelvin enters the cold room, to see the body of Gibaryan, and discovers a dead man next to the very black woman he has seen in the hall - a lively and warm despite the icy cold. Another striking detail is her bare feet: they are not erased and deformed by walking, their skin is soft, like baby’s.
Calvin decides that he has gone crazy, he is a psychologist knows how to verify this. He arranges a self-check and concludes: "I am not crazy. The last hope is gone. "
At night he wakes up and sees Hari beside him, his wife, who died ten years ago, she had killed himself because of him, Kelvin. She is in flesh and blood, and completely relaxed - as if they had parted yesterday. She wears a dress that he remembers, an ordinary dress, but somehow without zippers on the back, and her feet, like that Negro’s, soft like infant’s. It seems she takes it all for granted, is happy, and wants only one thing: even for an hour, never leave Kelvin. But he has to get away, to sort somehow out the situation. He tries to tie Hari and finds out that she is not like human strong. Kelvin is in horror. He lures the ghost of his wife in a single rocket and sends her to the circumplanetary orbit. It would seem that this nonsense is over, but Snaut warns Kelvin that in two or three hours, the "guest" will return, and finally says what, in his opinion, is happening. Haunting "guests" are sent by the Ocean of the planet Solaris.
That Ocean has already more than a hundred years occupied the minds of scientists. It is not out of the water, but of protoplasm, which moves in a strange and monstrous way, intumescents and creates a giant, meaningless in appearance, constructions, in the depths of which time changes its flow. No one knew why, and for what they are created. This living Ocean seems to have a unique function: it supports an optimal orbit of the planet around the Sun. And now, after a hard hitting of the radiation research, it began to send for no purpose phantoms of people, removing them from the depths of the human subconscious. Kelvin is lucky, the woman he once loved is sent to him, and some other receive their secret erotic desires, not even implemented ones. "Such a situation ... - Snaut said - one can only think, and then in a moment of intoxication, fall, madness, and aven a word may became flesh." So believes Snaut. He also says that the "guest" most often occurs while the person is asleep and his mind is off. At this time the area of the brain responsible for memory, is more available to the unknown rays of the Ocean.
Scientists could have left the station, but Kelvin wants to stay. He thinks he would not get to know anything about the Ocean, but wants to learn something about himself. The next night Hari appears again, and as in former times, they become lovers. In the morning, Kelvin sees in the cabin two absolutely identical white dresses with red buttons - both cut along the seam. This shock is followed by another: Hari by accident remains under lock and with superhuman strength, injuring himself, breaks out the door. Shocked Kelvin sees her wounded hands almost instantly heal. Hari is also very terrified, because she considers herself an ordinary, normal person.
Trying to figure out how Hari is "arranged", Kelvin takes her blood for analysis, but an electron microscope shows that the red corpuscles are not made of atoms, but as if out of nothing - apparently of neutrinos. However, the neutrino molecule can not exist outside of a particular field. Physicist Sartorius accepts this hypothesis, and starts building an annihilator of neutrino molecules to destroy the "guests". But Kelvin, as it appears, does not want it. He has recovered from the shock and enjoys his newfound wife - whoever she is. Hari is beginning to understand the situation, all its tragedy. At night, while Kelvin is asleep, she gets a tape left by Gibaryan for Kelvin and listens to his story about the "guest" and learning the truth, tries to commit suicide. She drinks liquid oxygen. Kelvin sees her agony, painful bloody vomiting, but radiation of the Ocean restores neutrino flesh in few minutes. Revived Hari is in despair, now she knows what torments Kelvin. Kelvin says in response that he loves her, not the earthly woman who killed herself for love for him.
It's true, and he is at a loss: he is to return to the Earth, and the beloved woman can only exist here in the mysterious field of the Ocean. He does not know what to do, however, agrees to the Sartorius’s proposal to record the currents of his brain and send them in the form of X-ray radiation beam to the Ocean. Maybe after reading this letter, the liquid monster would stop send its phantoms to people. The ray beats the plasma, but nothing happens, only Kelvin begin to see painful dreams in which he seems to be studied, disassembled into atoms, and then composed back again. The terror experienced in these dreams cannot be compared with anything in the world. So several weeks pass, Hari and Kelvin get attached to each other more and more, and Sartorius meanwhile, holds some terrible experiments, trying to get rid of the "guests". But Snaut says that “Faust” on the contrary seeks the remedy for immortality. Finally one night Hari gives Kelvin sleeping pills and disappears. Sartorius secretly from Kelvin creates the Annihilator, and Hari of great love for Kelvin decides to die - as once she did before. She's gone into oblivion, gone forever, for the invasion of the "guests" is over.
Kelvin griefs. He dreams of revenge, to burn the protoplasm to the ground, but Snaut manages to reassure him. He says that the Ocean did not want anything bad, on the contrary – it tried to make gifts to people, give them the most expensive, what has been hidden most deeply in memory. The Ocean could not know the true meaning of this memory. Kelvin takes this idea and as if calms down. In the last scene he sits on the shore of the Ocean, feeling its "gigantic presence, powerful, relentless silence", and forgives him everything: "I do not know anything, but still believe that the time of cruel miracles has not ended."
