Doctor: Peter Capaldi (Twelfth Doctor)
Jenna Coleman – Clara
Jami Reid-Quarrell – Veil
Directed by Rachel Talalay
Written by Steven Moffat
Script editor Nick Lambon
Produced by Peter Bennett
Executive producer(s) Steven Moffat
Incidental music composer Murray Gold
Series Series 9
Length 55 minutes
Originally broadcast 28 November 2015
After witnessing the death of his companion Clara Oswald ("Face the Raven"), the Doctor is teleported into a glass chamber within an empty castle, surrounded completely by water. The castle is constantly reconfiguring itself and resetting its rooms. He finds himself followed by a cloaked figure called The Veil. When the Veil corners the Doctor, he admits he is afraid to die; suddently the Veil halts and the castle reconfigures itself, allowing the Doctor to escape. He comes to see the castle and the Veil as part of a trap to obtain confessions from him. He has inner monologues, envisioning himself on the TARDIS answering questions that a silent Clara writes on a chalkboard. Exploring the castle, he comes back to the transportation chamber to find the word "bird" had been written in a pile of dust. Other clues direct him to find a room numbered "12".
The Doctor eventually locates Room 12 while the Veil is chasing him. Inside is a wall of Azbantium, a mineral 400 times harder than diamond. He realises that "bird" refers to "The Shepherd Boy", a fairytale by the Brothers Grimm, featuring a bird which slowly weathers away a mountain with its beak. In his inner monologue, where he despairs that he does not know how to escape this trap, Clara turns around and tells him to get over her death and figure a way to escape. The revitalized Doctor starts punching at the wall until the Veil touches him, burning him and disabling his regeneration process. The Doctor crawls back to the room he first arrived in and uses the last of his energy to restart the teleportation chamber, aware that due to the resetting rooms, the system will still contain a copy of himself. He then falls to the ground, writes "bird" in the dust, and disintegrates. A new Doctor appears, starting the cycle anew.
Eventually, after more than two billion years, the Doctor has finally broken through the Azbantium and a bright light vanquishes the Veil. The Doctor steps through to find himself on Gallifrey; behind him sits his Confessional Dial which he had been trapped in. A young boy approaches and the Doctor tells him to let the Time Lords know that he has returned, having "taken the long way around". The Doctor then proclaims "The Hybrid, destined to conquer Gallifrey and stand in its ruins, is Me."