The introduction introduces us to Lady Pendragon aka Guinevere, heir to Excalibur, and how she has to fight against Saxons and her own kind.
We then flash forward to our era and Jennifer Drake, a scholar specialising in the life of Guinevere. She is kidnapped so that she can become the new Lady Pendragon and deal with Morgana Le Fey and Mordred again. Lots of flashbacks reveal how Guinevere fared.
Very wordy with explanation and angst in places, it is a good read with a science fiction element at the end.