Park Si-on (Joo Won) is an autistic savant who was sent to a specialized care center as a child, where he was discovered to have a genius-level memory and keen spatial skills. He eventually enters the field of pediatric surgery as a resident, where he is given six months to prove himself capable. However, due to his atypical mental and emotional condition, Si-on faces conflict from his peers and patients, who view him as childlike and unreliable. Most critical is the hotheaded surgeon Kim Do-han (Joo Sang-wook), who labels him a soulless robot of a doctor who can only rely heavily on his photographic memory instead of feeling what the patient needs. Despite help from understanding and fair colleagues like Cha Yoon-seo (Moon Chae-won) and Han Jin-wook (Kim Young-kwang), the hospital is a fierce and competitive world, and the challenges Si-on faces become only greater when he falls in love with Yoon-seo.