We are introduced to psychologist Chris Kelvin as he navigates his daily life, which includes his morning rituals, commuting to work, and conducting group therapy sessions with patients. Despite this routine, there is a palpable sense of sadness lurking beneath Chris's exterior, a theme that unfolds as the story progresses.
One evening, while preparing dinner, Chris inadvertently cuts his finger and examines the wound under running water — a moment that will prove significant later. Shortly after, he receives an unexpected visit from two men bearing an urgent video message from his friend Dr. Gibarian, who is stationed aboard the Prometheus, a space station orbiting the mysterious ocean planet of Solaris. Dr. Gibarian's message implores Chris to come to the station, hinting at a momentous event that he should see for himself. The urgency heightens as the men reveal that contact with the Prometheus has been lost, and an intervention team sent to investigate has vanished, pushing Chris into a reluctant journey to uncover the fate of the crew.
Upon his arrival at the nearly deserted space station, Chris is met with a scene of chaos and bloodshed. He stumbles upon a makeshift morgue, where he grief-strickenly identifies Dr. Gibarian among the deceased. As he leaves, he fails to notice blood slowly pooling above him, foreshadowing the horrors yet to come.
The only survivors are an eccentric young man named Snow (Jeremy Davies), who provides unhelpful and cryptic answers regarding the situation, and Dr. Gordon (Viola Davis), who has locked herself away, grappling with trauma. Snow discloses that Dr. Gibarian took his own life and that another doctor was killed during a failed escape attempt by the intervention team. Meanwhile, a mysterious boy is spotted wandering the station, which Snow claims is Dr. Gibarian's son — an enigma that only adds to the emotional and psychological turmoil Chris must navigate.
After coaxing Dr. Gordon out of her seclusion, Chris finds himself haunted by dreams of his late wife, Rheya. In a shocking twist, he wakes up to find her in his bed, a manifestation of his memories, though he knows this Rheya cannot be real. His desperate attempt to rid himself of her by launching her away in an escape pod leads to a desperate emotional breakdown.
Snow explains to Chris that the alien planet Solaris has the power to read minds and manifest the deepest yearning of its victims, which in Chris's case is Rheya. As his second encounter with Rheya unfolds, she appears unaware of her own previous existence, leading to complex questions about identity and reality. Chris struggles to maintain his relationship with this new manifestation, but as Rheya begins to develop her own consciousness, remnants of her past begin to seep through, haunting her with memories of depression and unspeakable sorrow, including a past abortion and her own suicide.
A meeting among the remaining crew members reveals a diverging philosophy regarding these visitors, with Chris determined to believe in a second chance at happiness with Rheya. They contemplate the consequences of vaporizing these apparitions, particularly after Gordon argues that such actions may effectively erase their humanity, while Chris chooses to cling to hope against dire warnings.
As the situation escalates, Rheya becomes increasingly tormented by her existence, culminating in yet another heartbreaking suicide attempt. When Chris returns to find her body and insists she should not exist, a struggle between love and the ethical implications of her revival ensues. Chris's determination to keep her alive leads to an inevitable confrontation with Dr. Gordon regarding the implications of their actions.
In a shocking discovery, Chris learns about the secret life of Snow, uncovering the truth of who they all truly are. Ultimately, the tension culminates in Chris facing a pivotal choice about the nature of his existence as the space station begins to descend toward Solaris.
In a poignant conclusion, Chris finds himself back on Earth, confronting his own reality, though it remains uncertain whether he ever escaped the haunting presence of Solaris or if he has simply returned—as the line between life, death, and what is truly real continues to blur. As he catches a glimpse of Rheya once more, Chris is left to ponder the nature of existence in a world governed by longing and regret. The profoundly ambiguous ending raises questions about the essence of love and life itself, blurring the boundaries of reality and desire.
