: The episode reveals a mind-bending loop where the Doctor has lived and died for 4.5 billion years . Each "version" of the Doctor burns himself to power the teleporter, creating a fresh copy of himself from the machine’s hard drive, only to repeat the cycle to chip away at a wall of Azbantium —a mineral 400 times harder than diamond. Key Characters & Entities
: Delivers a tour-de-force performance, essentially carrying the episode alone. He uses a "Mind Palace" version of the TARDIS to process his thoughts and solve the puzzle of the castle. "Doctor Who" Heaven Sent(2015)
Following the death of Clara Oswald, the Doctor is teleported into a remote, shifting castle surrounded by a vast ocean. He is pursued by a slow-moving, hooded creature known as , which is designed to scare him into confessing his deepest secrets. : The episode reveals a mind-bending loop where
: It was nominated for the Hugo Award for Best Dramatic Presentation (Short Form) . He uses a "Mind Palace" version of the