Dave Martyniuk, Kevin Laine, Kimberly Ford, Jennifer Lowell, and Paul Schafer are students at the University of Toronto. They are approached by Loren Silvercloak, a magician, who invites them to the celebration of King Ailell in the world of Fionavar. Everyone accepts the invitation except Dave, who doesn't arrive in Brennin with the others. The Kingdom of Brennin is going through a severe drought, brought on by the king's unwillingness to sacrifice himself to the Summer Tree.
Kimberly succeeds Ysanne as the Seer of Brennin and is gifted with powerful artifacts to aid her work. Kevin and Paul join Diarmuid on a journey to the Kingdom of Cathal. Paul sacrifices himself on behalf of the king. He is pinned to a tree for three days until he resolves his past trauma. The drought comes to an end and Paul is renamed Pwyll, Lord of the Summer Tree. Jennifer is kidnapped after going out to ride with Brendel of the lios alfar.
Mount Rangat erupts and Maugrim is freed from his incarceration of a thousand years. King Ailell dies of a heart attack and Diarmuid ascends to the throne, becoming the new king. Dave finally arrives in Fionavar after getting stuck in limbo. When everyone is finally gathered in Brennin, King Diarmuid summons them for a council meeting. It is discovered that King Matt of the Dwarves freed Maugrim from his prison. Kimberly has a terrible vision of the future and to prevent it from coming true, she takes the five away from Fionavar and back to their home world.
