Dark moon of Avalon - Anna Elliott

Reunited after a hard-fought but tenuous victory, the young former High Queen Isolde and her friend and protector Trystan are sent on a dangerous quest to keep Lord Marche from usurping the throne of Britain through the brute force of his Saxon allies. This time, they must act as diplomats, persuading the rulers of each of the smaller kingdoms, from Ireland to Cornwall, that their loyalty to King Madoc is needed to keep Britain from the hands of a despot. With the combined influences of Isolde's cunning wit and talent for healing, and Trystan's strength and bravery, they must win the loyalty of a kingdom to fight for the side of right. .

Though Trystan has protected his identity for years, he has been exposed to the one person he's feared the most - his father, Lord Marche, who now understands the threat his estranged son will prove to be. With admissions of love hanging in the air, both Trystan and Isolde feel that their presence puts the other at greater risk. But when their situation is at its most desperate, they must finally confront their true feelings towards each other, in time for a battle that will test the strength of their will and their hearts.