Joon Ho and Yoo Mi 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, first daughter Kyung Joo and youngest daughter Jin Hae. 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 moves in next door to them. Mi Hee is a beautiful woman and Yoo Mi misunderstands the relationship between her husband and Mi Hee.