Caillean assumes the role of High Priestess of Avalon and becomes foster mother to Gawen who, though raised as a Druid, receives lessons from the Fairy Queen.

Gawen is killed the day after their wedding as he tries to protect Avalon from the Christians, who were formerly tolerant of the Druids but now have a fanatical leader, and a Roman patrol sent to find him and bring him back for punishment as a deserter.

When Dierna receives a vision about the new Protector of Britannia, a Roman admiral named Carausius, she forces Teleri into marriage with him.

This part opens as the High Priestess Ana sends the Druid bard Taliesin to escort her third daughter, Viviane, to Avalon.

Viviane had been fostered on a farm, but when she is fourteen years old, her mother recalls her to Avalon to take the place of her two older sisters, who had died.

Although Viviane chafes at what she considers to be an unjust restriction, her virgin state enables her to become the first woman in centuries to handle the Holy Grail, which is kept by Taliesin's order of Druids.

[3] Publishers Weekly called Lady of Avalon a "splendid" prequel that "combines romance, rich historical detail, magical dazzlements, grand adventure and feminist sentiments into the kind of novel [Bradley's] fans have been yearning for.