The couple, Hyuk and Kyung, both working people have marital problems; the wife, Hyuk having a stagnating sex life because she is always exhausted. One night she again rejects Kyung’s advances and he goes to bed feeling hurt and angry. The next morning, they discuss their problems and decide to take a romantic weekend trip to add fire to their marriage. But when Hyuk fails to perform, they are back to square one. The following Monday, Hyuk tells Woo, his colleague about the failed trip with his wife. Woo and his wife, Sook are swingers. So he suggests him swapping partners by joining a secret club called Club Butterfly. Hyuk has been already receiving a mysterious emails from an anonymous sender urging him to join this illicit club. Neither Hyuk nor Kyung knows what is in store for them.