On her way home from work, Na-mi loses her smartphone, containing everything about her. Jun-yeonh finds Na-mi's phone and returns it to her, but after installing spyware. By tracking her everyday life, he learns all he can about Na-mi - her whereabouts, hobbies, tastes, work life, finances, and social network - and approaches her by concealing his true identity. In the meantime, police detective Ji-man finds traces of his son Jun-yeong at a murder crime scene and secretly investigates Jun-yeong, suspecting the worst.
