The Doctor and Ace go to the Festival of Britain, 1951, while searching for the Timewyrm. However they find Britain has been conquered by the Nazis.
- Bavarian Fire Drill: The Doctor does this very well, first sending two members of the Britischer Freikorps back to headquarters when they start bullying the Jewish proprietor of a tea stall, then pretending to be a party official with a badge he took from the dying Reichsinspektor General.
- Evil Cripple: Dr Kriegslieter (the War Chief). An aborted regeneration has left him with two fused bodies.
- Ghostapo: A Nazi mystic cult. Their power turns out to be based on alien technology.
- Godwin's Law of Time Travel: It was bound to happen in Doctor Who eventually (technically the series had toyed with the idea before, both with the Daleks and with the parallel universe from "Inferno", but this is the first time it's been explicitly stated).
- Hitler's Time Travel Exemption Act: The Doctor has to stop Ace killing Hitler. He points out that without Hitler someone more competent might lead the Nazis.
- Literary Allusion Title: To the Book of Exodus.
- Piggybacking on Hitler: The War Lords are collaborating with the Nazis in order to get the resources for their own agenda, and plan to overthrow Hitler when he has outlived his usefulness.
- Power Born of Madness: The Timewyrm tries to possess Adolf Hitler and is instead trapped in his mind by his madness.
- The Quisling: Mr Arnold.
- La Résistance: Ace has some trouble with them due to her association with the Doctor.
- The Starscream: The War Chief hopes to eventually overthrow Hitler and put Himmler in place. Subverted in that Himmler is loyal to the Fuhrer and refuses to follow this plan.
- Stupid Jetpack Hitler: The War Chief and War Lords are trying to help the Nazis. Then there is the Timewyrm inhabitating Hitler.
- This Is My Name on Foreign: In wartime Germany, the Doctor translates his occasional makeshift identity of "Dr John Smith" into German, presenting himself as "Dr Johann Schmidt".
- Those Wacky Nazis: The Nazis are not totally wacky, but are played with a lighter tone than they might have been.
- Timey-Wimey Ball: It turns out the timeline where Hitler used the Timewyrm's power to invade Britain resulted from the Doctor travelling back to prevent this timeline. The Doctor works this out and travels forward to release the Timewyrm.
- Virgin Sacrifice: Ace almost becomes one. This may seem surprising given her later reputation, but this is one of the earliest novels.
- We Didn't Start the Führer: Played with. Hitler separately receives covert assistance from two different groups of aliens attempting to further their own ends — but neither is able to control him, and what he does with their assistance is all entirely his own idea.