Eight-year-old Grace Davitt's mother, Anna, an ornithologist, once saw a monster in the lake near their Vermont home. She believes it may be a dinosaur that has somehow escaped extinction and each morning she photographs the dark water, hoping it will reappear. To Grace, the monster is more evidence that the world is full of mysterious things most people will never see. From her boy-genius babysitter, she has learned about invisible black holes from which no one can escape. From her mother, she has heard about the hyena men of Africa who devour their wives in their sleep. From 'The Encyclopedia of the Unexplained', she has learned about children raised by wolves and men who suddenly burst into flames.
It is only Grace's father, a dedicated rationalist, who tries to convince her that the world is, in fact, well-ordered and reasonable. For him the only truth is science, and, increasingly, he finds himself shut out by Anna as she draws Grace deeper and deeper into a strange world of myth and obsession.