Connie Willis' Oxford Time Travel series is based in the History department of Oxford University in the mid-twenty-first century. In this future time travel was discovered, but when the space-time continuum prevented anyone from making a profit, the whole enterprise was turned over to the academics for study. In the first book of the series, The Doomsday Book, we meet historians who are studying the coming of the Black Death in Europe. Thus is time travel established as a way for researchers to obtain a first-hand account of many of history's most significant eras and events.
We are also told about "slippage," a phenomenon that occurs, ostensibly, to prevent historians from disturbing the flow of the space-time continuum, and changing history (i.e., you can't go back in time and assassinate Hitler). Slippage is the variation between the date and time set for the historian's arrival and the actual arrival. Variation (apparently) is generally minutes or hours, but as we see in the third and fourth book in the series (which make up a sub-series of their own), when slippage becomes weeks and months, it is worrying.
Blackout and All Clear, which really is an 1100-page book divided into two volumes, takes us from 2060, to 1944, to 1940-41, back to 2060, then back to 1941 via 1995 ("wibbly-wobbly, timey-wimey" indeed as another time traveler once remarked). The books follow the story of three historians who are studying various aspects of Britain during World War II and their eventually stranding in the past. I found the story of Polly, Eileen, and Mike and the variety of contemps ("contemporaries," those who actually belong in the past) surrounding them to be equally compelling as both science fiction and historical fiction.
As the story jumps back-and-forth among a number of times and settings, the reader gradually sees the connections and the intertwining of both the space-time continuum ("normal" timeline) and the timelines of the characters. Polly's first research assignment was in 1944-45, followed by a jump to 1940-41. Based on this, she knew what would happen because for her it already had happened (see, "wibbly-wobbly"). According to Willis, and her Oxford History Department, historians cannot affect history, but, is that really true? This becomes the central question for Polly, Eileen, and Mike, and the reader is pulled into the question and forced to examine the forces of correlation and causation that may--or may not--exist.
Blackout and All Clear can very well be read on their own, as for the most part very few characters carry over from The Doomsday Book and To Say Nothing of the Dog, however, all four books are very engaging, and should be enjoyed by fans of science fiction, historical fiction, and (in the case of To Say Nothing of the Dog) mysteries.
