Secret Garden follows the unlikely romance between Kim Joo-won, an eccentric and arrogant CEO of a high-end department store, and Gil Ra-im, a humble and dedicated stuntwoman. Their lives collide when Joo-won mistakes Ra-im for an actress, leading to a series of comedic misunderstandings and a growing fascination that challenges his elitist worldview. Despite their vastly different social statuses and personal struggles, they find themselves drawn to one another. The narrative takes a fantastical turn when the two become trapped in a mysterious forest and drink a strange floral concoction, causing them to swap bodies whenever it rains. This supernatural phenomenon forces them to experience each other's lives, struggles, and hidden vulnerabilities, ultimately bridging the gap between their worlds. As they navigate the complications of their swapped identities, they must confront family opposition, professional pressures, and the deep-seated secrets that threaten to tear them apart.