Peril in Mechanistria was the fifth short story published in the Doctor Who Annual 1966.
During an escape from the Daleks on Skaro, the TARDIS' space-time locator is damaged. The Doctor cannot accurately pilot the TARDIS. He is happy when it lands and decides to rest for the night before exploring his new surroundings.
The following morning, the Doctor finds the ground of this world is made of metal and there is a strange, throbbing hum in the air. As he investigates the metal terrain, a huge robot (later identified as a Grukker) almost runs him over but he is rescued by unseen persons and loses consciousness.
When the Doctor awakes, he finds himself in the company of primitive-seeming humans calling themselves the Korad and calling their world Korad as well. The Doctor learns this world has no soil nor seas nor plant life, just machines that the Korad use. When asked where he comes from, The Doctor says too much about the TARDIS before he realises the Korad are more mechanically savvy than they first appeared.
Drako, the leader of this haven (encampment) of Korad mechanics, takes the Doctor prisoner and sends for the Wise Ones from another haven. While he is held, Drako explains that machines are the masters of this world. The Korad are only allowed to live because of their usefulness to them. Drako pleads with the Doctor to help plan an escape for the mechanics before the Wise Ones arrive and take the TARDIS for themselves. As the Doctor devises a plan, Beran, one of the Wise Ones, arrives to interrogate him.
Beran announces he will examine the TARDIS to learn its secrets before destroying it. When the Doctor objects, Beran informs him that the first law of the Mechanistrians, the machine rulers, is that no machine that was not made on the world, which is Mechanistria, not Korad, is allowed to remain there.
The machines of the world, Beran reveals, house human brains. Among the Wise Ones, who call themselves Mechanistrians, having their brain used in the a new machine is the highest honour. When joined into the machine, a Wise One gains the knowledge of all other machines and a type of immortality.
As Beran finishes his explanation he momentarily lets his guard down. Drako wrests Beran's small, gun-like atomizer from him and forces Beran to follow as he and the Doctor head toward a small aircraft to get to the TARDIS. Once in the air, Drako, refusing to shoot Beran, forces him to jump from the craft.
Landing close to the TARDIS, Drako turns the atomizer on the Doctor and demands he take him back to a time before the Mechanistrians began their rule and prevent it from happening. The Doctor, at first worried that Drako may attempt to overpower him and take the TARDIS for himself, finally agrees to transport him.
After the trip, the Doctor opens the doors to the world that is known at this time as Korad. Drako exits, kneeling down to feel the grass and looking up to see clouds that no Koran had seen in thousands of years.
The Doctor, accepting Drako's thanks, closes the doors and continues on his journeys. He notices that the atomizer, which Drako left behind, has vanished, which he takes to mean that Drako succeeded in his task.
- One of the machines on Mechanistria is a soarer.
- The space-time locator is damaged again in PROSE: The Playthings of Fo.
- Two Korads and a Mechanistrian went shopping at the Frenko Bazaar. (COMIC: Bazaar Adventures)