Kim Sun-woo is an enforcer and manager for a hotel owned by a cold, calculative crime boss, Kang who assigns Sun-woo to a simple errand while he is away on a business trip; to shadow his young mistress, Hee-soo, for fear that she may be cheating on him with a younger man with the mandate that he must kill them both if he discovers their affair.

Hyang-Mi lives with her husband Dong-Hyeok and her 6-year-old daughter Eun-Ju. Since her husband is in Seo Rak Mountain due to his work, Hyang-Mi feels loneliness. Whenever she feels lonely, Hyang-Mi soothes her loneliness watching videos. As weekend comes, she goes to the mountain to meet Dong-Hyeok. However she hears that her husband meets a mute girl called Sun-Nyeo from maidservant