The Doctor Falls the episode, the Doctor (Peter Capaldi) must save himself and the remaining human population of a gigantic colony ship from Mondas, while also dealing with two different incarnations of the Master (Michelle Gomez and John Simm) at once. The episode features a cameo from the First Doctor, now portrayed by David Bradley. He had previously played William Hartnell, the original First Doctor actor, in the 2013 "Doctor Who" docudrama "An Adventure in Space and Time". Aboard the colony ship reversing from the event horizon of a black hole, the Doctor finds Bill has been converted into a Cyberman. The Master
Space and Time (Doctor Who) TARDIS suddenly shakes and the lights go out. The Doctor asks Rory if he dropped a thermal coupling, which Rory admits to and apologises for doing. Amy then apologises as well and, at the Doctor's confusion, explains that Rory was looking up her skirt through the glass floor when he dropped the thermal coupling. The Doctor then notes that they have landed through "emergency materialisation" which should have landed the TARDIS in the safest space available. The lights come on, revealing another TARDIS inside the control room — the TARDIS has materialised inside itself. The Doctor experimentally walks through the