The Spectre of Edgar Allan Poe (1974)

Poe's fiance, Lenore, falls into a coma and is taken for dead. She is rescued at the last possible moment from being buried alive, but the experience has driven her insane. On the advice of his friend, Dr. Forrest, Poe commits Lenore to the asylum run by Dr. Grimaldi. On a visit to the asylum, Poe and Forrest sense that something strange is going on, and decide to sneak back in after dark and investigate.