Nick Bannister, a private investigator of the mind, navigates the alluring world of the past when his life is changed by new client Mae. A simple case becomes an obsession after she disappears and he fights to learn the truth about her.
- In the near future, climate change has led to rising sea levels and temperatures, working hours during daytime has become too unbearable for people. They work, recreate, and socialize through the dark of night instead while contending with drastically rising sea levels in most coastal cities.
Nicolas "Nick" Bannister, a self-esteemed private investigator living in Miami, administers thiopental to his clients which places them in a machine to assist with reminiscence. He works with his assistant Emily "Watts" Sanders in contract work for the Miami-Dade District Attorney's Office.
One day, a walk-in client, Mae (Rebecca Ferguson), arrives asking for his help in finding a missing key she has been looking for. Nick is immediately attracted to her; he starts following her to a nightclub where she works as a chanteuse singer. Nick and Mae quickly fall in love but, unbeknownst to Nick, Mae is revealed to be working for a drug kingpin whose product consists of an addictive substance called "Baca".
Mae soon disappears shortly after her date with Nick, leaving him with only his memories. Nick tries to relive these memories by immersing himself in the incubator tank, despite Emily warning him not to do so, as it can cause brain damage.
One day, Nick and Emily are called by the DA to conduct an immersion evaluation on a crime suspect, who happens to be Mae. A simple case soon becomes an obsession after her disappearance as Nick soon finds himself in a fight to learn the truth about her past.
At the peak of Nick's obsessive investigation, the truth is revealed - the son of a land baron hired Mae to seduce Nick and steal the memories of his client Elsa (Angela Sarafyan), who'd been having an affair with his father (Brett Cullen). Mae and corrupt police officer Booth (Cliff Curtis) ended up tracking down Elsa and her son. Booth kills Elsa while Mae turns on him to help her son escape. Booth later kills Mae, but not before she leaves Nick a message in Booth's memory, which Nick then "walks" into. Mae reveals that she did genuinely love him and tried to get back in touch with him, but missed her chance.
Nick takes the evidence and reveals Walter's son Sebastian (Mojean Aria) as the mastermind, hoping to avoid sharing his inheritance with his half-brother. He also reveals where the boy has been hiding even since Mae saved him - at a white stilt-house in the middle of the water, where Mae had lived for a time before she came to Miami.
Concluding his investigation, Nick permanently puts himself in his memories, partially as a sentence for his actions, which included trapping Booth in a painful memory forever. It's then revealed that the entire film has actually been taking place in Nick's memory decades later, which might mean certain details aren't exactly how it really happened, with an older Watts arriving to check on her old friend in the memory tank, accompanied by her granddaughter (Nico Newton).