The Japanese Empire is pressuring President John F. Kennedy to cede Hawaii to them, isolating Australia. The President has promised "No more surrenders", but everyone knows this will lead to a war the US cannot win.
A possible solution has been found. It has been discovered that the Nazis were aided by time-travelers from the future; perhaps this America can send people back to prevent this disaster in the first place. A crack team of scientists and commandos go back to save the present by fixing the past.
The book provides examples of:
- Alternate History: Two of them: the original pre-intervention timeline, where WWII never happened, and the modified one where Hitler was given atomic weaponry. The resulting timeline after the second intervention is ours.
- Day of the Jackboot: Inverted: uptime characters in London boggle at all the buildings that were Nazi headquarters in their time, but are still British.
- Godwin's Law of Time Travel: Intervention by hostile time-travelers let Hitler win in the first place.
- Historical Domain Character: Lots. In addition to the political leaders at the time like Franklin D. Roosevelt, Neville Chamberlain, and Winston Churchill, many important scientists like Enrico Fermi show up. One key insight comes when Albert Einstein finds a short story written by a neighborhood teenager named Isaac Asimov...
- I Am One of Those, Too: A character undercover on a train in Nazi Germany claims to be an archaeologist. Another passenger says he, too, is an archaeologist, and starts talking about their field. The undercover character throws him off by making it clear his archaeology was only to prove the superiority of the Aryan Germans.
- Make Wrong What Once Went Right: The goal of the hostile time-travelers: have Hitler take over the world for them.
- My Future Self and Me: Winslade, who originally came from the good future.
- Set Right What Once Went Wrong: The main plot. Doomed to failure, in a way, because time-travel is based on the many-worlds theory. The protagonists could never save Kennedy's America because their arrival created a new universe.
- Sexy Secretary: Hildegarde. When it becomes too obvious that she is carrying on with Lieutenant Colonel Boeckel, she gets reassigned.
- Stupid Jetpack Hitler: Hitler could have never won without help from uptime.
- Temporal Mutability: Branching Timelines-style. The past can't be changed, but a new universe where it was can be created. The people in the old timeline are still stuck, unless they travel to the new one.
- Year Inside, Hour Outside: Time flows at different rates between 'uptime' (the future) and 'downtime' (the past).
- Young Future Famous People: Isaac Asimov is a teenager who wants to be a writer.