The Doctor and Adric have materialised in a chamber. It is dark and decaying, and has many archways leading from it. Adric catches a glimpse of two cowled figures, one tall and one short, but they are gone before he can show the Doctor. Another cowled figure approaches and removes his hood. He greets the Doctor and Adric by name and introduces himself as Mauritz.
He leads them through many passages, but doesn't answer any of their questions. They pass through a great hall in which cowled monks are writing at desks. After passing through a library they arrive at a dormitory. He offers them bowls of soup, but whenever the Doctor asks where he gets his supplies, Mauritz merely replies, "We make the most of that which we have." The Doctor and Adric decide to save their soup for later, so Mauritz takes them to the citadel.
On the way they see monks repairing sections of wall. They pass through a garden in which many monks work. The Doctor approaches one monk, who refuses to answer his questions. The Doctor removes the monk's hood, revealing an older version of Mauritz. He removes several more hoods. Each face is Mauritz, at different ages.
Mauritz explains. The monastery is a five-dimensional space mapped into three dimensions. The citadel does not merely allow access to the future, it allows access to all possible futures. Any paradox that occurs will either stabilise or collapse. Mauritz created this place so that he can learn from all his other selves.
He offers to take the Doctor and Adric back to the TARDIS, but they want to see more. At one point, Adric looks out of a window and sees three monks of different heights. They return to the dormitory, and their soup, but the Doctor realises that the meat in the soup comes from versions of Mauritz that have died. They at last understand Mauritz' saying: "We make the most of that which we have." There is no waste in the monastery; every bit of the dead is used in some way.
When Mauritz notes that he now has company, the Doctor and Adric head for the TARDIS at a run. When they near the TARDIS, however, it dematerialises, leaving them behind. Mauritz enters the chamber, accompanied by several monks with different heights than Mauritz, and explains what happened. He had offered the choice for them to leave in the TARDIS earlier. Since every possible future exists in the monastery, there were two versions of the Doctor and Adric. There was the Doctor and Adric who chose to leave, who they just saw depart in the TARDIS, and there was the Doctor and Adric who decided to stay, the two now standing in the empty chamber, with no TARDIS to escape in. The other monks remove their hoods, revealing that they are different future versions of the Doctor and Adric. Mauritz proclaims that the two were always with him, and welcomes them to the monastery.
to be added
- This story is narrated by Adric.