Before the Big Flood, Liz Green worried more about hiding detention notes, the activities of her rebellious friends, and the onset of mental illness than global climate change. She lives on the Texas Coastal Plain with her single mother, brilliant older brother, and socially awkward but clever younger brother. But now the water keeps rising, and her mother, Leah, has bigger problems than Liz. The suburban family, their neighbors, and billions of people all over the world are stuck between the rising seas and snarled land escape routes.The military cannot cope with millions of refugees, and the wealthy or connected rush to berths on secret ocean habitats.Liz's family finds a website called "RaftPeople.com" which coordinates the efforts of ordinary people who plan to construct homemade crafts in order to float out of the disaster. They have to reply upon the natural talents of Liz's younger brother, Mark, a middle aged former female special forces diver named Shirley, and an eighty year old retired naval engineer. This small group of neighbors decides to become Raft People to escape before their Houston suburb floods.