Ji-su moves in as a lodger at the home of sisters Mi-ae and So-jeong. On her very first night there, So-jeong stumbles home drunk with her boyfriend, Seong-ha, completely forgetting Ji-su is staying with them. She carelessly opens her bedroom door and the two begin getting intimate. As Ji-su watches their passionate encounter, her gaze locks onto Seong-ha’s body, unable to look away…
