Joon-goo is an innocent man in his 30s. He quit his job and runs a small BBQ place with his young and sexy wife, Mi-ri. Then one day, Mi-ri's sister, Na-ri, comes to their house. Na-ri is in her mid-20s. Joon-goo feels attracted to Na-ri who is calm and considerate, unlike minx Mi-ri. The two end up crossing the line after a small happening...