In 1953, a 27-year-old factory worker named Henry Molaison --- who suffered from severe epilepsy --- received a radical new version of the then-common lobotomy, targeting the most mysterious structures in the brain. The operation failed to eliminate Henry’s seizures, but it did have an unintended effect: Henry was left profoundly amnesic, unable to create long-term memories. Over the next 60 years, Patient H.M., as Henry was known, became the most studied individual in the history of neuroscience, a human guinea pig who would teach us much of what we know about memory today. Luke Dittrich’s investigation into the dark roots of modern memory science ultimately forces him to confront unsettling secrets in his own family history.