Tae-suk (Jae Hee) is a loner who drives around on his motorbike, taping takeout menus over the keyholes of front doors and breaking into apartments where the menus have not been removed. He lives in those apartments while their owners are away, washing their clothes and mending their broken appliances while usually playing "Gafsa" by Natacha Atlas on their CD player. When he breaks into one large home, he is unaware that he is being watched by an abused housewife Sun-hwa (Lee Seung-yeon). Tae-suk leaves after making eye contact with Sun-hwa, but then returns. He witnesses Sun-hwa's husband abusing her and proceeds to catch his attention by practicing golf in the yard. He hits Sun-hwa's husband with golf balls and then leaves with Sun-hwa.
The couple begins a silent relationship, moving from one apartment to another. At one home, after drinking, they are caught by the returning owners, sleeping in their bed and wearing their pajamas. They also get into trouble with the law when they break into the home of an elderly man who died alone. They proceed to give him a proper burial. When the man's son and daughter-in-law arrive at the apartment, they assume that Tae-suk and Sun-hwa killed him. The couple is interrogated by police, but remain steadfastly silent. An investigation reveals that nothing was stolen from any of the houses and the old man died of lung cancer. Sun-hwa's husband arrives to take her home, and bribes the policeman in charge of the investigation to allow him to strike Tae-suk with golf balls. Tae-suk ends up attacking the police officer and is sent to jail. There, he practices golf with an imaginary club and balls and develops his gifts for stealth and concealment, frustrating his jailers by remaining out of sight.
After being released from prison, Tae-suk rejoins Sun-hwa in her house, using his skills to evade her husband's detection: standing behind the man and moving as he turns, even kissing Sun-hwa over her husband's shoulder (as seen in the poster). Sun-hwa appears to say "I love you" to her husband, but reaches out for Tae-suk. The husband leaves on another business trip, after which Sun-hwa and Tae-suk embrace.