The original Psycho novel by Robert Bloch was published in 1959 and became an instant hit, leading to the smash movie only a year later, which brought Norman Bates' terrifying story into the public consciousness, where it still remains (proven by the success of the TV series Bates Motel). It took Bloch 23 years to write another Psycho novel, revealing that Norman had been in a mental institution the entire time. In that sequel, Norman quickly escapes the sanitarium and goes on a killing spree in Hollywood.

But what happened in that asylum during those two decades? Until now, no one has known.

It's 1960. Norman Bates is in the State Hospital for the Criminally Insane, and it's up to Dr. Felix Reed to bring him out of his catatonic state.

But Norman and Dr. Reed have obstacles in twisted fellow patients and staff members who think of the institution as a prison rather than a place of healing. And the greatest obstacle is the building itself, once a private sanitarium, rumored to be haunted. A wild card appears in the persona of Robert Newman, Norman's twin brother, taken away at birth after the attending doctor pronounced him brain damaged. As Robert and Norman grow to know each other, Norman senses a darkness in Robert, even deeper than that which has lurked in Norman himself.

Soon murders begin to occur, and a shocking chain of events plunges us even deeper into the deranged madness inside the walls of Psycho: Sanitarium.