In some cases, the machine used for time-travel will refuse to function, rendering the trip impossible. Historians in Willis' world believe that the laws of physics resist possible alterations to the past by preventing time-travel to certain places or times. They can return from the same location when someone in the future re-opens the Net for them at an agreed-upon 'rendezvous' time. The time-travel device, a portal called 'the Net', remains in the time-traveler's present, while sending the time-traveler to a particular location (called 'the drop') and time. In their world, time-travel has been known since the early 21st century.

The research is mainly conducted at the University of Oxford in England in the mid-21st century. Willis imagines a near future (first introduced in her 1982 story ' Fire Watch' and featured in two of her previous novels: Doomsday Book and To Say Nothing of the Dog) in which historians conduct field work by traveling into the past as observers. These two volumes are the most recent of four books and a short story that Willis has written involving time travel from Oxford during the mid-21st century, all of which won multiple awards. The diptych won the 2010 Nebula Award for Best Novel, the 2011 Locus Award for Best Science Fiction Novel, and the 2011 Hugo Award for Best Novel.

The second part, the conclusion All Clear, was released as a separate book on October 19, 2010. Locus Award for Best Science Fiction Novelīlackout and All Clear are the two volumes that constitute a 2010 science fiction novel by American author Connie Willis.

Blackout connie willis