Cynnes Tarth has a secret. The people have forgotten what lies within the fog, but they do remember to be careful. Don't let the children play too much in warmlake. Don't go into the forest. Most of all, don't show any interest in the brinlins that live among the reeds. But Marim, a young Tessilar stranded on the island, doesn't know the rules. In hopes of establishing herself as a healer, she agrees to see a boy who is wasting away no matter how much he eats. When she recognizes his affliction as magical in nature, she must deduce what no one can tell her if she hopes to save his life.