Moon Gang-tae is a psychiatric ward worker who has dedicated his life to taking care of his autistic older brother, Moon Sang-tae. They frequently move from town to town due to Sang-tae's sensitivity to loud noises, a result of witnessing their mother's murder. Gang-tae is known for his kind-hearted nature, patience, and unwavering dedication to his brother. Despite facing numerous hardships, he remains strong and supportive, always putting Sang-tae's needs first. His journey takes a turn when he meets Ko Moon-young, a famous children's book writer, and begins to heal from his own emotional wounds while helping others.