The Celestials are Faeries who live in the trees. Their homes resemble bird nests or bee hives, but are very spacious inside. They pursue the occupations of astronomy, astrology, weather forecasting, ship building, navigation and sailors in general. This story centers on Hugh, the son of Aoife. Aoife is a priestess. Her mother, Moira Holly, was high priestess, but as the story begins, she has just died. Through election by the priestesses, Aoife, who was high priestess for the Mercifuls, has now been made Chief High Priestess. Hugh is not the pious, dutiful son. He's a bit of a rogue with the ladies. In fact, his reputation has gotten so bad that his mother must intervene and threaten him that if he doesn't mend his ways, he may lose his apprenticeship. Hugh has been apprenticed to a master in the Celestials. He dreams of being an astronomer. But Hugh doesn't have enough of a gift for astronomy, and his master decides that he would be better suited to learn navigation. He goes to see Aoife in hopes she agrees. She is relieved that at least Hugh hasn't embarrassed the family, and quickly agrees that if this is what Hugh wants, she has no objection. Meanwhile, one of Hugh's friends wonders why Moira, who wasn't even 100 yet (young for a Faery), has died. This sets Hugh to wondering, and he brings his suspicions to Aoife. After some investigation, Aoife discovers that all is not as it seems in the House of the Priestesses. At the same time, Hugh discovers Moira's sister, Zoe, who was once a priestess, is now a Vampyre, and a member of Shauna Faun, the band that most of the youth of their clans are enchanted with. Hugh visits his Uncle Teilo. Teilo was once a thrall of the Vampyres, and is married to Aoife's sister, Jessica. Their son, Bran, is an acolyte druid. Through Teilo, Hugh manages to contact the Vampyres and asks for Zoe's aid in discovering who might have wished ill on his grandmother. She doesn't know much, but gives what aid she can. Hugh's apprenticeship goes well, and he becomes a journeyman navigator who is so good at his job he is much sought after by ship captains. On one trip, their ship is captured by pirates. These are no ordinary pirates, but Vampyres sent by an old enemy of Simon Mallow's (Simon is the leader of Shauna Faun.) Hugh is captured and offered for ransom in exchange for Zoe or Flynn, two of the other members of Shauna Faun. Meanwhile, Aoife discovers that Moira was killed, and who killed her. These priestesses are put on trial, and their ringleader is condemned to death. Before she leaves the court, she accuses Aoife and Moira with conspiring with Vampyres, and the druid, Dandriloc, who is the Chief Druid, must decide Aoife's innocence or guilt.