Yoon Jin-A (Son Ye-Jin) is a single woman in her 30's. She works as a supervisor at a coffee company. Yoon Jin-A is an easygoing person, but she feels empty inside. Seo Joon-Hee (Jung Hae-In) is the younger brother of her best friend Seo Kyung-Sun. He comes back to South Korea after finishing work abroad. Yoon Jin-A though he was just a childish guy, but he appears different to her now.