In the episode, the alien time traveller the Doctor (Matt Smith) and his companion Clara Oswald (Jenna-Louise Coleman) bring two kids Angie (Eve de Leon Allen) and Artie (Kassius Carey Johnson) to an extraterrestrial theme park, where an army of cyborgs called Cybermen reawaken centuries after their defeat in a war.Clara relocates the platoon to elsewhere in the park and they take stock of minimal arms: one large anti-Cyberman gun with a limited charge, five hand pulsers, and a planet-imploding bomb.The Doctor returns with Angie and Artie, and demands that Clara tie him up to let him finish his chess game, while the platoon hold off poorly against the Cybermen, who can quickly adapt and upgrade to overcome any obstacle.Lead writer and executive producer Steven Moffat contacted Gaiman about writing for the series and asked him to make the Cybermen "scary again".[6] Angie and Artie, the kids Clara babysits, were portrayed by Eve de Leon Allen and Kassius Johnson respectively,[7] who previously appeared in "The Crimson Horror"."[28] Ross Ruediger of New York Magazine wrote that Gaiman "created an amazing yet believable world here — one that felt otherworldly and yet close to home.[19] Sarah Crompton at The Daily Telegraph felt that Gaiman succeeded in making the Cybermen scary again, though the episode "could have done with more variation in pace and tone".Mulkern thought the Cyber Planner-possessed Doctor scenes were "the principal failing of the drama [...] despite Matt Smith's gallant efforts", and compared it to the 1988 serial Silver Nemesis, which he labeled "execrable".[7] Gaiman later admitted that the episode was not the best, adding that it "left him with 'a bad taste in [his] mouth'" and inspired him to take more creative control with Good Omens (2019–present) as its showrunner.