Key Of Light / Morrigan's Cross by Nora Roberts

Key of Light: The pleasure of your company is desired for cocktails and conversation. 8pm, 4th September. Warrior's Peak. You are the Key. The lock awaits. When Mallory Price decides to attend the event she discovers that she and two other women are the only guests of their mysterious hosts. They are told an amazing story of three demi-goddesses who have been cast into an eternal sleep and in every generation, three women are born who alone have the power to free them. If one fails, they all lose. If they all succeed a new destiny awaits.

Morrigan's Cross: Standing on the cliffs of 12th century Ireland Hoyt Mac Cionaoith is visited by the goddess Morrigan and is charged with saving his and all future worlds. Now, Hoyt, a sorcerer, must travel through time to find and train the five others to join him and battle against the vampire queen Lilith. Fate brings him first to Glenna Ward - a modern witch. They find themselves drawn together, but is their love strong enough to survive not just the battle ahead but the centuries that separate them?