Gu Seo-jin is a cold-hearted chaebol heir who runs the Wonderland amusement park and suffers from Dissociative Identity Disorder, stemming from a childhood trauma. Due to his condition, whenever his heart rate exceeds a certain level, his sweet, gentle alternate personality, Robin, emerges. Complications arise when Seo-jin attempts to shut down the park's circus due to an incident, pitting him against Jang Ha-na, the passionate master of the circus. As Ha-na tries to save her troupe, she finds herself entangled with both the icy Seo-jin and the warm-hearted Robin, unaware at first that they inhabit the same body. While Seo-jin fights to keep his condition secret and maintain control of his company against internal threats, a dark past involving a kidnapping resurfaces, putting everyone in danger and forcing the dual-natured man and Ha-na to confront deeper emotional truths.