The Forests of Avalon is part of Marion Zimmer Bradley’s Avalon series, of which the most famous is The Mists of Avalon. I had read Mists before Forests, and they both work as stand-alone novels. This series is based in the time of legend: Forests describes how the priestesses of Great Britain handled the power balance with the male Druids under the Roman empire.
The plot has strong links to modern-day feminist issues, combined with rivalry and betrayal. The main plot line remains throughout one of a forbidden love, and the impact this has on the lives of all characters as the lovers try to avoid damaging the institutions to which they are loyal.
The start to this book is a little slow, but it is a strong story with well written characters whose dilemmas and bitterness are very realistic.