Clara (Jenna Coleman) is struggling to balance travelling with the Doctor (Peter Capaldi), teaching at Coal Hill School, and her boyfriend, ex-soldier Danny Pink (Samuel Anderson). The Doctor tells Clara he will have to go under deep cover, but he shows up as caretaker of the school. It seems a murderous robot called the Skovox Blitzer (voice of Jimmy Vee) is nearby and has already killed a community support officer. The Doctor has been planting time displacement vortex devices around the school to send the threat into the far future, and he has an invisibility watch to sneak up on it.

Danny watches Clara with the Doctor and becomes suspicious. He finds one of the devices and interferes with its settings. When the Doctor sets it off, the Blitzer only moves 74 hours into the future. Danny accosts Clara, calling her an alien, and she says she loves him. The Doctor calls this a boyfriend error. Clara lets Danny use the invisibility watch to see how she interacts with the Doctor. But he knows Danny is there. A student named Courtney Woods (Ellis George) has noticed the TARDIS and starts following the Doctor. At Parents’ Evening, the Blitzer materializes. The Doctor and Clara trigger the Blitzer’s self-destruct by accident, but Danny helps them shut it down. The Doctor offers to let Courtney come along when he dumps the Blitzer in space, but Courtney throws up in the TARDIS. Back on Earth, Danny warns Clara not to let the Doctor push her too far. Meanwhile, the dead community support officer wakes up in the promised land, or the Nethersphere.

Positive reviews admired Capaldi’s comic timing, as do I. At his best, he reminds me of Christopher Lloyd in Back to the Future. Many, however, were less than impressed with the Skovok Blitzer. Ellis George was singled out for praise as Courtney Woods. There was some rather rich character development in this one. The Doctor whistles “Another brick in the wall,” as he observes the school. One of Pink Floyd’s videos of “One of These Days” was inspired by Doctor Who.