"...Add venom from your greatest fear -- One drop -- and then the truth is clear."

Rowan and his mother have journeyed to the Maris folk on the coast to do their duty. Rowan's mother is to choose the new Keeper of the Crystal, who will lead the Maris when the old Keeper dies. Rowan is to be ready to take her place if she should be killed. Her death is a distinct possibility.

Then Rowan's mother is poisoned, and he boldly breaks a thousand-year-old tradition. He refuses to choose a candidate using the customary tests until all three candidates help him find the antidote for his mother. Armed with just a cryptic rhyme, the four set forth to face perils they can't even imagine. Will they figure out the meaning of the rhyme in time to save Rowan's mother? Can they survive the deadly creatures that await them? And even if they do, what will happen when the hidden dangerwhich threatens everyone in the land -- reveals itself?