The fifteen-year-old Murry twins, Sandy and Dennys, are accidentally sent back to a strange Biblical time period, in which mythical beasts roam the desert and a man named Noah is building a boat in preparation for a great flood.
A hermit lives on an island where he has peace and quiet, until a small bird comes to share the island with him, but when the bird leaves, the hermit realizes that his island was much better with the bird than without it.
Biblical text and illustrations depict how Noah and his family were singled out by God to be saved from the great flood, along with two animals of each kind.
Dark clouds gather as Yessa walks to her brother's place, telling a story as she goes about the early days of the earth; and the animals follow her two by two to listen.