Winner of the 2011 Hugo Award for best novel.

In her first novel since 2002, Nebula and Hugo award-winning author Connie Willis returns with a stunning, enormously entertaining novel of time travel, war, and the deeds - great and small - of ordinary people that shape history and, alarmingly perhaps, the future.

The year is 2060, the fourth decade since the invention of time travel by a scientist who would not have been born had Hitler won World War II. At Oxford University, historians jockey for plum assignments, to carry out first-person research in the era of their specialty, from the Crusades to the Plague or the aftermath of the devastating nuclear attack on London.

In the face of increasing scientific criticism of time travel - and the possibility that it could shatter the space-time continuum - three academics are in the heart of World War II in England. Merope is a maid in a country house studying evacuated children in England in 1940. Mike is researching a common thread of heroism across history and is on his way to Dunkirk. Polly lives as a shopgirl during the Blitz, watching the behaviour of ordinary citizens under stress.

For all three, unknown corners of history explode as Hitler's bombs rain down on London. But when they try to return they find themselves unable to make their way back to the future. Have they broken the law of time travel and changed the narrative of history in some accidental way? A dreadful awareness comes over them all: far from witnessing the past, they may be on a journey into the utterly unknown. And the world they left in 2060 may no longer be there to save them.