Yoon Hyewon, an assistant at Yuseon Airlines, finds herself caught in the middle of a power struggle within the company while secretly working as a spy. Despite having grown up in tough circumstances, Hyewon was able to graduate school and secure a job at a major corporation thanks to Yuseon Airlines’ scholarship program. However, Vice President Ha Jiseok informs her that it's time for her to repay the company’s kindness. He assigns her to monitor his cousin, Executive Director Ha Taebeom’s every move, and report back to him. Taebeom, fully aware that Hyewon is working for Jiseok, still keeps her close, using every opportunity to make her life difficult. But as time goes on, what started as a purely professional battle begins to take an unexpected turn as the two find themselves drawn to each other.