The incredible story of Henry Gustave Molaison, known only as H.M. until his death in 2008. In 1953, at the age of 27, Molaison underwent a dangerous "psychosurgical" procedure for his debilitating epilepsy. The surgery went horribly wrong, and when Molaison awoke he was unable to store new experiences. For the rest of his life, he would be trapped in the moment.