Couple Jin-goo and Joo-hee have been experiencing a lover's slump after their marriage. Meanwhile, a new couple in the neighborhood, Hyun-jin and Yoo-jeong came to the other couple's house to introduce themselves. They're attracted with each other's husbands and wives, and in the end, crosses the line that is not supposed to be crossed within neighbors. After that day, two couples' passion intensifies....