Connected by phone in the same home but 20 years apart, a serial killer puts another woman’s past — and life — on the line to change her own fate.

Seok-geun, an ex-rollercoaster-designer-turned-taxi-driver, loves his wife, Dam-deok. What he also loves is playing with fire on secret nights out. But Dam-deok’s sudden death leaves Seok-geun miserable and heartbroken. Bong-soo is the boring and prude husband of Seok-geun’s sister, Mi-young. His Italian restaurant business looks lackluster, and so is his marriage, until he meets Jenny, who later gets a job at Bong-soo’s restaurant. Fond of Jenny’s personality and good humor, Mi-young decides to hire Jenny as a housekeeper for her brother, Seok-geun, to keep him company. Will these four people be able to get along with one another?