In 2060, Oxford's historians travel routinely into the past, and the Second World War is the assignment everyone wants. Michael Davies is bound for Dover and the small boats of Dunkirk; Merope Ward is in Warwickshire under the name Eileen O'Reilly, minding evacuated children at a country manor; Polly Churchill takes a shopgirl's job on Oxford Street so that she can spend her nights in the Underground shelters and watch the Blitz from the inside.
Each has been drilled in the rules: observe, do not intervene, and above all do not alter the course of events. What none of them expects is for the drops to close behind them. Cut off from 2060 with no retrieval team in sight and their deadlines slipping past, the three are thrown together in a London of falling bombs, blackout curtains and rubble-strewn mornings, where the only reliable information is what they carry in their own heads and their foreknowledge grows less trustworthy by the day.
Willis's portrait of wartime Britain is meticulous and warmly comic even as the danger mounts, and beneath it runs a colder question: whether the historians have already done something to the past that cannot be undone.