The novel takes place during the third ‘Quarter Moon event,’ the first two occuring in 970 and 986 AD.
After the end of the first event, shared technology caused the deaths of thousands of Saxons and Danes. During the second event, a series of protocols were introduced to prevent the mixing of people from different eras and a repeat of the earlier catastrophe.
Following the death of her husband Leofric, Ealdorman of Cumberland, Beatrische knows help will not come from the 19th or 26th centuries, unless she can contact a mythical future community her daughter insists is real.