After losing her job due to her looks, Hyo-jung, a self-assured and eager woman, visits a mysterious yoga institute recommended by her dramatically transformed friend. This institute is managed by a former actress. During the intensive training program, a young yoga instructor named Nani informs Hyo-jung and four other women that only the one who excels in the course will uncover the secret to eternal beauty. The participants must adhere to five strict rules over the week-long course: 1. refrain from eating, 2. avoid showering for an hour post-class, 3. steer clear of mirrors, 4. remain inside the building, and 5. refrain from contacting anyone. As the training progresses, the women are tempted to break these rules due to their hidden desires, and Hyo-jung begins to suspect that there is more to this institute and the ageless actress than meets the eye.