The seventeenth season of the realistic drama about the thrills and sadness of working women in their 30s, centered around a single woman named Lee Young-ae.

When an American fitness club opens a branch in Korea under corporate pressure, a new manager comes with it. With a wonderful, distracting new figure, Manager Jenny has the attention of all of her staff.

Missing and death cases take place in succession along the Korean Demilitarized Zone. South Korea forms a unit led by Captain Jo Jin-Ho and First Lieutenant Shin Yoo-Hwa as assistant leader. They are given only 24 hours to find out the truth behind the incidents. Team members find evidence, but they feel like something isn't right.