Joon-Ho (Park Hee-Soon) and Yoo-Mi (Jin Kyung) have been married for 20 years and they are still madly love in with each other. The couple have three children: first son Chul-Won (Jang Sung-Bum), first daughter Kyung-Joo (Yoon Bo-Ra) and youngest daughter Jin-Hae (Lee Go-Eun). The parents have difficulty having sex at night, because their youngest daughter Jin-Hae keeps going into their bedroom. One day, Joon-Ho’s female friend Mi-Hee (Hwang Woo Seul Hye) moves in next door to them. Mi-Hee is a beautiful woman and Yoo-Mi misunderstands the relationship between her husband and Mi-Hee.