Mi-yeon, who was adopted by Si-yeon's parents when she was a baby, lives with Si-yeon and her husband, Hyoung-bu. One day, no longer able to control her sexual desires, she seduces Hyoung-bu, and their forbidden relationship begins. When Mi-yeon discovers that her sister's been unhappy and having an affair, she decides to end her relationship with Hyoung-bu out of guilt.
