Nina, a full-time homemaker, discovers that her husband, Jasper, is hiding a disturbing secret—and she is determined to expose him. Every night, Jasper spends two hours sitting in front of the fish tank, claiming that watching the fish helps him relax. But when Nina’s best friend, Sunny, comes over to feed the fish, she is suddenly overcome with terror. She begs Nina to call the police before fleeing the house. Moments later, she falls into the river and dies, clutching a small plasticine fish made by Nina’s son, Danny. As the police investigate Sunny’s death, Nina discovers a hidden compartment in the base of the fish tank. Inside are a screen and a headphone jack, revealing that Jasper hasn’t been watching fish at all—he has been secretly monitoring someone. Her investigation leads her to Vivian, a woman in a vegetative state who turns out to be Jasper’s legal wife and the rightful owner of his river-view apartment. To continue collecting the monetary compensation for housing relocation and annuity insurance payments under Vivian’s name, Jasper and his mother, have concealed his bigamous marriage while keeping Vivian under constant care and surveillance. Sunny discovered the truth about Vivian, making her a target of Jasper’s harassment by the river. Her death was no accident. Determined to bring the truth to light, Nina joins forces with Vivian’s younger brother, Seth, to seek legal guardianship, report Jasper to the police, and submit crucial evidence. With the help of drone footage and other evidence, the police uncover the full extent of the deception. Jasper and his mother are finally investigated and held accountable. Nina returns the apartment to its rightful owner, Vivian, and starts a new life with Danny. Meanwhile, Vivian gradually begins to regain consciousness, offering hope for a new beginning.