David Haller, AKA Legion, is a troubled young man who may be more than human. Diagnosed as schizophrenic, David has been in and out of psychiatric hospitals for years. But after a strange encounter with a fellow patient, he’s confronted with the possibility that the voices he hears and the visions he sees might be real.

Dr. Gregory House, a drug-addicted, unconventional, misanthropic medical genius, leads a team of diagnosticians at the fictional Princeton–Plainsboro Teaching Hospital in New Jersey.