Tae-suk, portrayed by Jae Hee, is a solitary figure who roams the streets on his motorbike, sticking takeout menus over the keyholes of front doors and infiltrating the apartments that haven't removed them. He silently resides in these homes while their owners are away, tending to their chores, fixing broken appliances, and documenting his stay with selfies alongside their belongings.
During one of his escapades, he happens upon a grand residence where he unknowingly catches the gaze of an abused housewife and former model, Sun-hwa. After an initial departure following their brief eye contact, he returns to uncover the harsh reality of Sun-hwa's life; her husband, Min-gyu, is a brutish man who mistreats her. In an attempt to intervene, Tae-suk resorts to an unusual method by practicing golf in the yard, throwing golf balls in Min-gyu's direction, igniting a confrontation. Ultimately, Tae-suk helps Sun-hwa escape her tormentor.
As Tae-suk and Sun-hwa embark on a profound yet silent relationship, they traverse through various apartments, where Tae-suk continues honing his golf skills by creating makeshift setups with balls strung through cords around tree trunks. Their adventures take a turn when they are discovered in bed, clad in the owners' pajamas, resulting in a dramatic altercation with a boxer who punches Tae-suk mercilessly. The subsequent misfortunes lead to a freak accident where Tae-suk's golf practice inadvertently injures an unsuspecting car passenger, leaving him burdened by guilt while Sun-hwa offers solace.
The couple shares a tender moment in a traditional hanok, sipping tea and exchanging a kiss, only to later stumble upon the lifeless body of an elderly man in another apartment. Out of respect, they decide to organize a burial for him. However, their good intentions quickly turn to misfortune when the deceased man's family arrives, prompting them to assume that Tae-suk and Sun-hwa are responsible for his death. During intense police questioning, they choose to remain silent, leading to the confiscation of Tae-suk's camera. The investigation reveals no thefts had occurred, and the old man’s death was due to lung cancer.
The story takes a dark twist when Min-gyu, determined to reclaim Sun-hwa, colludes with a police officer, using bribery to rain down golf balls on Tae-suk. This ignites a fierce response from Tae-suk, resulting in his imprisonment. Within the confines of the jail, he channels his frustrations, engaging in imaginary matches, sharpening his stealth and evasion skills, much to the annoyance of his captors.
Upon his release, Tae-suk swiftly returns to Sun-hwa by leveraging his newfound stealth abilities to remain hidden from Min-gyu. In a poignant moment, she feigns affection for her husband while secretly kissing Tae-suk over his shoulder. When Min-gyu departs for a business trip, Tae-suk and Sun-hwa share an intimate moment together on a scale, leaving the audience pondering with the text: "It's hard to tell whether the world we live in is either a reality or a dream."
