Merlin's Daughters tells the Arthurian tale from the standpoint of Gwyneth, the Fairy Queen. Her evil twin, Guenevere, has stolen Excalibur. Gwyneth and Nimue venture into the Human Realm to protect Excalibur, and they become caught up in the drama of Arthur's court.

The story also reveals how the Arthurian stories came to be told in so many variations – and why.