The Harpers, once a heroic family of witches, are broken. The loss of Chris and Holly's daughter was the final straw in a series of heartbreaks and now they've given up on fighting for the greater good.

New secrets help point to the fate of their daughter. Working together again, they struggle to reclaim the life they once had, but ten years away from each other comes with consequences. Tensions are high as each witch grasps at every opportunity to restore their family, including working with former enemies.

While the witches learn to work with each other again and move on from the past, they leave themselves susceptible to the influence of the Fire Wizards and the Pentad, demonic supergroups that may be the end of them.

The Blue Moon is the fifth and final book in the Under the Moon series, which is a part of the Art of Magic universe, containing the Lost By Magic and the Coven series.