Jay, an international student from Thailand, comes to Korea to see his friend Sung Hoon. The two enrolled in the same college "Health and Happiness" class, and need to submit a physical body assessment for their final project. While Sung Hoon already works out regularly, Jay isn't in the greatest shape, and he struggles in the gym. Enter Jin Wook, a personal trainer who takes a special interest in Jay, much to Sung Hoon's displeasure. However, there's something strange about Jin Wook – despite his kindness toward Jay, suspicions begin to rise that Jin Wook may be involved in a murder and missing person incident. Is there a happy ending in store for Jay and Sung Hoon, or will Jay's budding relationship with Jin Wook cost him an unspeakable price?