Choi Jeong-in

Ace NIS agent Jung Hae-seong is demoted after a mission failure. He goes undercover at a high school to locate King Gojong's missing gold, meeting his teacher Oh Soo-ah, who sees him as her lost first love, stirring old heartbreak.

Cho Yeo Hwa has been a widow for 15 years. Her in-laws are the most prestigious noble family in the kingdom. During the day, she leads the life of a widow devoted entirely to her dead husband's memory and rarely ventures outside the gate of her home. At night, Yeo Hwa dons the mask of Hero, who secretly jumps over the surrounding wall to save the helpless.

It follows the story of middle-aged office workers struggling to survive in a turbulent workplace.