plot synopsis from: https://en.wikipedia.org/wiki/Hide_(Doctor_Who)
In 1974, Professor Alec Palmer and his assistant Emma Grayling collect photographic evidence of a ghost, known as the Witch of the Well, in the Caliburn mansion; Alec uses Emma’s strong psychic powers to create an emotional connection that appears to summon the ghost. They are surprised by the arrival of the Doctor and Clara, claiming to be from military intelligence. The Doctor shows interest in the investigation after Clara points out that the ghost appears in the same position within each photograph. As they investigate, Clara finds that Emma has feelings for Alec but which are seemingly not reciprocated; at the same time, Emma warns Clara about sensing “a sliver of ice” within the Doctor’s heart.
The Doctor and Clara find a location in the mansion which is noticeably colder than the rest of the house, and the group feels as if they are being watched. Suddenly, the house grows cold, and Clara feels something holding her hand; the two race back to where Alec and Emma are waiting to see Alec’s equipment activating on its own accord. A thin black disc materializes in front of them, and Emma senses something crying “help me” through her psychic abilities before the disc vanishes and the house returns to normal.
The Doctor takes Clara in the TARDIS to examine the specific spot at several points during the Earth’s history, and comes to the conclusion that there is a gateway to a pocket dimension there that is collapsing rapidly, and that someone - the person behind the ghost - is trapped within it. The Doctor asserts he cannot use the TARDIS as its energy would be drained as soon as it materialised, and instead helps to prepare a device to stimulate Emma’s psychic abilities to open the gateway. He further constructs a tethered vest and means to pull him back across once he crosses over.
When the Doctor crosses over, he finds himself in a forested area, a small bit of land floating in a void. He meets Hila Tukurian, a time traveller and the woman stuck in the pocket dimension, who warns him that something else is there, following them. They race to the gateway, seeing an echo of the Caliburn house appear in the pocket dimension and try to barricade themselves from the creature to give them time to return. The Doctor insists Hila go first, and though she is successfully saved, the gateway closes due to Emma’s exhaustion, leaving the Doctor trapped in the forest with the fast-moving creature. Drawn by the sound of the TARDIS’ cloister bell, Clara races to the TARDIS, finding it locked. She pleads with the device to let them save the Doctor, and the TARDIS lets her in. The TARDIS briefly appears in the pocket universe, flying close to the ground to allow the Doctor to jump and hang onto it before the creature can grab him. The Doctor and the TARDIS safely reappear in the normal world.
As the Doctor and Clara prepare to leave, the Doctor tells Emma the real reason he stopped at this point was to ask Emma if she could sense anything unusual about Clara, but Emma reveals that there is nothing strange, but does reveal that Clara is, “more scared than she lets on”. The Doctor offers Hila a lift to any other place in history, but as he discusses the matter with her he reveals that she is the future descendant of Emma, and the blood connection is what allowed Emma to open the gateway to rescue her. Further, he states that Hila is also the future descendant of Alec. Contemplating the bonds that love can create, the Doctor then realises that there is another entity within the Caliburn house. He implores Emma’s help one last time to rescue the creature from the pocket dimension and reunite it with its mate.
Discuss.