From the back of the book:
Eiranwen, the bride of the evil Raven-King Lord of the Unseelie, has fled, taking his unborn child to Faerie, to rear the demi-god as she would. But she was snared by the Raven-King's Hag and suffered beneath the sorcery of the old woman. When at last she called upon the druids they knew that champions must be gathered, champions willing to fight the Raven-King's hold upon her.
But things are not always as they seem when dealing with the fey and the Unseelie in particular.
This module is designed for four to five players of 5th to 6th level.