Jang-hyeon is in the leasing business and he lives with his son Byeong-cheol. One day he gets a call from his daughter-in-law in the States that she's coming to Korea for a while and will be staying at Jang-hyeon's house. Jang-hyeon goes to pick her up from the airport and Byeong-cheol calls his girlfriend for some mature fun, but the daughter-in-law walks in.

Da-hyeon and Hyeon-soo grew up like sisters without their parents, and still live together even after Da-hyeon got married. Sex isn't good between Da-hyeon and her husband, so when her husband is out, she has an affair with a stranger. One day, Hyeon-soo's step-father, Seok-hyeon, goes to his son's house and sees his son's wife's sister there all by herself...