Sunah still breastfeeds her 9-year-old daughter Jiah. Every morning, after her husband Jicheol and Jiah leave the house, she locks herself in the bathroom, turns on the water, and spends time alone. One day, her downstairs neighbor complains about water leaking in their bathroom, and her mother Jeonghee shows up unexpectedly. Scared of not being able to spend alone time in the bathroom, her safe haven, she must accept the fact that her mother will be living with her.