Middle-aged man Gi-jun and a college drop-out In-ae meet on a plane to Busan. Their relationship grows stronger, and they finally become lovers. When Ji-suk, Gi-jun's wife finds out about their relationship, she also tries to have an affair with another man. In-ae decides to leave Gi-jun and her love for him behind as a beautiful memory. The marriage of Gi-jun and Ji-suk is saved at the brink of destruction.