DOCTOR WHO IN DETAIL

The Doctor has become a tutor at St. Luke's University, Bristol, and has invited Bill Potts to his room in the University. At 4pm Nardole shows her inside. The Doctor isn't there, and Bill takes the opportunity to look at some of the strange stuff om his desk, and the TARDIS sat in the corner. As the clock strikes 4 the Bill hears an electric guitar, followed shortly afterwards by the Doctor.

Although Bill is not a student at the University (she works in the canteen serving chips) the Doctor has seen her at some of his lectures. A lot of people attend the Doctor's lectures, but the Doctor noticed that most people frown when the do not understand something whereas Bill smiles. Even though she is not a student the Doctor offers to be Bill's personnal tutor.

She agrees to meet the Doctor as 6pm each evening. On one of evening's she spots the Doctor and Nardole running towards a University basement and follows where she overhears them trying to open a vault. She leaves before they notice her. Outside she notices a girl she met briefly in a bar - Heather. Bill notices a small defect in Heather's eye, and Heather asks Bill to follow her to a strange puddle and look at her reflection. Bill notices there is something odd about her reflection, but can't quite work out what is wrong.

Bill spends a bit of time at Christmas with the Doctor anbd tells him about her mother. Bill says her mother dies when she was a baby, and there aren't many pictures of her. Later, at home, Bills' foster mum, Moira, tells Bill she found a box of old photos of Bill's mother. In one of the pictures is a mirror, and in the mirror is a relection of the Doctor.

After Christmas Bill walks past the site of the strange puddle and sees Heather. Bill asks Heather to wait for her while she runs round the site, and Heather promises to wait. When Bill reaches the puddle there is no sign of Heather. Later Bill tells the Doctor about Heather, the strage puddle, and its strange reflection. As she's talking she looks out of the window and sees the Doctor running, and runs after him. 

Bill follows the Doctor to the puddle. The Doctor is quick to notice what the problem is with the relection. Heather spotted it because of her eye defect. Heather's face was not symmetrical, and the reflection was showing her face as it should be seen, not reversed. This means the puddle is not water, and the Doctor takes a sample. He also notices a ring of feint scortch marks around the puddle. After the Doctor and Bill leave the puddle starts to follow.

At home Bill hears someone in the shower and assumes it's Moira - until he receives a call from her. When she enters the bathroom there is no-one there, but the bath is wet, and there are wet footprints. She sees a shadow in the shower, but it's empty. The bottom is wet, and when Bill looks into the plughole she sees an eye.

Startled she runs to the Doctor. In the University ground she sees Heather standing by a tree - soaking wet. Bill talks to her, but Heather only repeats what Bill says. Scared Bill runs into the Doctor's room and barricades the door. Water runs under the door, and Heather emerges in the room. The Doctor suggests that he and Bill should pop into his box. At first it is dark, but the Doctor fires up the TARDIS and Bill gets her first view of the TARDIS.

Bill appears unfazed. She thinks it's a knock-through to another room, and that the Doctor has made the room himself. He's obviously run out of money when it came to the old wooden doors. Bill is more concerned with going to the toilet after a fright. That's when Nardole appears and tells her to give it a minute.

Bill is more impressed with the TARDIS when the Doctor takes it to the vault, which is still sealed and safe. But the water has followed them to the vault. Realising it is not the vault it's after, but them, the Doctor sees how far the water is prepared to go. He takes the TARDIS first to Australia, and then to a desolate planet 23 million years into the future. 

Discussing the water the Doctor realises that the scortch marks could have been left a shuttle, and that the puddle could have been the space equivalent of an oil leak. Heather was a little depressed and a desire to leave wherever she went. This meant the oil now has a pilot.

Whilst the Doctor and Nardole are talking Bill finds a puddle. Inside she sees Heather. When Heather reaches out and grabs Bill the Doctor and Nardole free her and they run back to the TARDIS as a fountain of space oil erupts.

The Doctor takes the TARDIS to the deadliest fire he can think of - a Dalek's. The Doctor and Bill run through a battle between the Movellans and the Daleks and find a lone Dalek. Heather follows them, and is fired upon by a Dalek, with no apparent effect. When trapped by Heather the Doctor realises why it will not leave. The last conscious thought of the real Heather was of waiting for Bill. The Doctor tells Bill she has to release Heather from a form of contract. Heather and Bill join for a moment - until Bill finally says goodbye.