Choi Soo Ah has spent the last twelve years working as an airline assistant purser and raising a daughter alongside her pilot husband. She is content; but when she meets Seo Do Woo, her life changes. The bright and warm Seo Do Woo is a married, part-time architecture instructor who also has a daughter. He, too, is content until a shocking incident brings confusion and Choi Soo Ah into his life. What will happen when their two lives collide?