The black cat Lin Xi has raised for five years suddenly undergoes a drastic change in temperament. A veterinarian determines that it has been replaced with an extremely aggressive foreign mutant cat. It has gone three months without eating and stares at her every night, suggesting a deliberate murder plot. Suspicion falls on her husband, Chen Bin. Every day, he feeds the cat imported salmon while bringing Lin Xi milk tea from the same shop. After drinking it, she always feels strangely drowsy. She secretly installs surveillance cameras and hires a lawyer to investigate. Every clue points toward the man sleeping beside her. Beneath the appearance of a loving marriage, a sinister conspiracy to use a pet as a murder weapon is closing in. What deadly secret lies behind the cat swap?