The result of that effort was still in the balance when, in last week's episode , they landed on a 400-mile-long spaceship containing both Cybermen (who captured and converted Bill into one of them) and Missy's own prior incarnation, the Master (John Simm).

Director Rachel Talalay creates some particularly macabre images in the scenes of the creatures being mowed down by the defenders' rifles and then fastened to wooden crosses like scarecrows while children look on, inured to the sight.

Suddenly, a shuttlecraft piloted by Nardole breaks through the ground, and a flashback efficiently fills in the details of how he and the others escaped from a swarm of Cybermen and made it to this agricultural level, about halfway down the length of the massive ship.

Most of the episode's focus is naturally on the regular characters, but a couple of villagers rise above being reduced to mere cannon fodder: the young girl Alit (Briana Shann) and Hazran (Samantha Spiro), the leader of the community who takes a shine to Nardole.

Meanwhile, the Master and Missy are working their way through the maneuvers of the other plot arc that spans “The Doctor Falls.” Most of the humor in this otherwise grim episode comes from these two, as Moffat exploits the comic possibilities inherent in two versions of the same person being present simultaneously.