Choi Soo-A works as an assistant purser at an airline. Her husband is a pilot and they have a 12-years-old daughter. Choi Soo-A thinks she is content with her life, but she meets Seo Do-Woo. Her life changes. Seo Do-Woo works as a part-time instructor in architecture. He has a bright and warm heart. He is married and they have a daughter, but a shocking incident occurs.