The Doctor is awakened by someone knocking on his door. When he answers it, he finds a crowd of people, including a reptilian couple and a seagull child. They direct his attention to a comet that is heading straight for the town. He tells them he will go to the bookstore to get information on how to stop the comet, but he first has to get his keys.
Back in his house, the Doctor is disorientated and soon becomes lost. He opens a door and finds that it leads to a coffee bar in which several young people in twentieth century dress are seated at tables. A young woman offers him tea. She introduces herself as Matilda, and she is a student of particle physics. She seems to know who the Doctor is, but thinks that he is at the coffee bar at the wrong time. The Doctor decides to try something. He closes his eyes, and when he opens them, he finds himself on an Earth colony he helped in a previous incarnation. He is in the middle of a crowd in a street. There are troops, and people are running. He joins them. He notices the troops are chased by golems, known as Implementation Units, or Imps, that had helped defeat an invasion of the planet on the Doctor's previous visit.
As the Doctor wonders if he can do something, his attention is grabbed by a boy with a dog's face. He shows the Doctor the comet in the sky, heading this way. Conveniently, the Doctor's bookshop is nearby. As he tries key after key, he notices that there is an Imp inside the shop. Before he can get further, he is approached by two teenage soldiers, a boy and a girl, who know he is the Doctor. They tell him the Imps have lost control. They put him in a suit of armour; he can't see or move. The Doctor figures out how to move the suit, and the boy switches on the visual. The Doctor is back in the coffee bar, and the patrons, including Matilda, huddle in a corner. The comet is closer, and there is an explosion. In the armour, the Doctor can feel the heat increasing.
The building collapses, and the Doctor and Matilda huddle in the wreckage, burning.
- The Doctor has recently regenerated.
- Matilda knows that the Doctor likes sugar in his tea.
- Someone has drawn roundels on two walls of the Doctor's bedroom.
- Although the story leaves it unclear exactly what is happening or why, the surreal, dreamlike events have led some fans to interpret it as a nightmare the Doctor is having.