Recursion

Detective Barry Sutton encounters Ann Voss Peters, a woman suffering from False Memory Syndrome, who has vivid memories of a life that never existed in her current reality. Despite Barry sharing his grief over his daughter, Ann, distraught by the loss of her son, commits suicide. This tragic event introduces the mysterious condition to Barry.

Neuroscientist Helena Smith, motivated by her mother's Alzheimer's, struggles with funding for memory preservation research. Billionaire tech magnate Marcus Slade offers her unlimited resources to develop a device capable of mapping and reactivating human memories. Helena accepts the offer, driven by her desire to help her mother, signing a strict confidentiality agreement.

On his deceased daughter Meghan's birthday, Barry meets his ex-wife. He later discusses the mysterious spread of False Memory Syndrome with his friend, Gwendoline, noting its connection to phenomena like the Mandela Effect. Barry frequently alters his own memories to cope with profound grief, highlighting the subjective nature of human recollection.

Helena arrives at Fawkes Station, Slade's isolated oil rig research facility. Slade emphasizes memory's value, encouraging Helena's work. She aims to create a 'time capsule' for core memories. However, Slade's push for more radical, non-dynamic applications of the technology raises early ethical concerns for Helena regarding the project's true direction and potential implications.

Barry experiences False Memory Syndrome himself, gaining a second set of memories where Ann Voss Peters' suicide never happened. He is later subjected to a mysterious procedure in a deprivation tank, which results in his consciousness traveling back in time to 2007. He successfully intercepts and prevents his daughter Meghan from being struck by a car, altering the timeline and saving her life.

Helena wakes in her apartment with a nosebleed and a second set of memories, realizing the chair allows consciousness to travel to the past. Slade reveals he originally met her in a different reality where he was her assistant, implying the world has been reset multiple times. He admits to using the chair to build his power, orchestrating Helena's life and manipulating timelines for his benefit.

Helena, horrified by Slade's manipulations and the ethical implications of 'dead memories,' uses the chair to send her consciousness back to 2007. She abandons her identity, hiding in the remote Yukon to prevent Slade from ever rebuilding the dangerous technology. Meanwhile, Barry cherishes his second chance with Meghan, finding his memories of the previous, painful timeline slowly fading.

Years later, on November 6, 2018, memories of the original timeline flood back into Barry, Julia, and Meghan. The city transforms with the sudden appearance of the Big Bend tower. Meghan, traumatized by remembering her own death, commits suicide. Barry is left devastated, having lost her again, wandering through a city made unrecognizable by conflicting realities.

Grief-stricken, Barry searches for the hotel where his timeline was reset. Helena, having foreseen a global catastrophe if police intervene, intercepts him. She explains that Slade recreated the chair, triggering the current outbreak of False Memory Syndrome. Helena proposes they infiltrate Slade's lab together to destroy the technology, and despite his immense grief, Barry agrees to the perilous mission.

After a failed mission where Barry dies, Helena is imprisoned by DARPA. Rajesh Anand recruits her to help master the government-rebuilt chair. DARPA establishes the "Department of Undoing Particularly Awful Shit" to prevent tragedies, initially with strict protocols. However, the chair's use gradually shifts towards military objectives and more dangerous, long-range interventions, causing widespread psychological trauma and reality shifts for the agents.

The chair's blueprints are stolen and leaked globally, leading to escalating chaos and destructive reality shifts. Witnessing the continuous destruction, Helena decides to use the chair herself to return to 1986 as her sixteen-year-old self. Her goal is to spend the next three decades preventing the chair's creation, meticulously documenting her previous lives to maintain her sense of purpose.

Barry experiences multiple catastrophic timelines with Helena, each ending in global memory outbreaks or nuclear war. He learns from Slade that the only solution is to return to the original timeline and prevent Helena's murder. Barry uses the chair to map a memory from the original timeline, ultimately rejecting destructive nostalgia and accepting life's dualities. He chooses to move forward into the original reality to prevent the chair's invention and approach Helena anew, beginning their relationship from scratch.