In the episode, the Doctor, Bill, Nardole, and Missy answer a distress call from a gigantic ship trying to escape a black hole.
The Doctor proposed to test Missy's atonement by having her, alongside Bill and Nardole, answer a distress call.
They are held at gunpoint by the solitary crew member, Jorj, who demands to know which of them is human, fearing creatures that are arriving by the lift.
The Doctor, Missy, and Nardole learn from Jorj that, two days previously, some of the human bridge crew had gone down to the lower level of the ship to start the engine reversal, but they never returned.
Razor, one of the hospital's employees, shows her around and explains that some of the patients are waiting to be "upgraded" for "Operation Exodus", to escape the polluted air of the ship's lower levels due to contamination from the fuel.
The Master says that he loves disguises, a fondness which dates back to his debut appearance in Terror of the Autons when he posed as a telephone engineer.
The website's consensus reads, "'World Enough and Time' sets up the conclusion of Doctor Who's tenth season with a cliffhanger episode that deftly blends many of the show's most important ingredients.
He stated that the opening scene of the regeneration was a "cheap tactic" with no answers given, but the idea of Missy filling the Doctor's shoes was far more interesting.
He also complimented Rachel Talalay's direction of the episode, after having a track record with Peter Capaldi's series finales.
[17] Giving the episode a perfect score, Patrick Mulkern of Radio Times called it "macabre and riveting", stating that the conversion of Bill Potts into the Mondasian Cyberman and the revelation at the end of the episode "packed more punch" than Jackie Tyler's Cyber-conversion in the second series or Oswin Oswald being revealed as a Dalek in the "Asylum of the Daleks".
Steven Moffat’s script deftly cuts between two scenes of revelation, expertly shot by director Rachel Talalay.