When the child Bridei is sent to the kingdom of Fortriu to be raised by Broichan, a powerful druid, he knows only that he must be studious and obedient. Bridei applies himself to learning, unaware that a secret council of elders, including Broichan, has long been working on plans for the future of their divided homeland, and that Bridei himself is central to their strategy.

When a baby girl is left on the doorstep one winter's night, Bridei thanks the gods for sending him a companion to share his lonely existence in the remote household. But Tuala's arrival spells a perilous complication to Broichan's master plan. As Bridei moves ever closer to his grand destiny, and as Tuala grows from fey child to beguiling young woman, powerful forces turn against the secret council; enemies will stop at nothing to foil the druid's plan, even if they must endanger Bridei's life.