Eleven hundred years after the apocalyptic destruction of the United States of America, peace between the remaining warring tribes has finally been achieved. Despite this peace, the Pelbar stronghold Threerivers retains its secretive and reclusive ways, keeping its distance from the other remaining tribes and guarding against change. A strict matriarchy, Threerivers remains the most conservative Pelbar community under the unquestioned and unyielding rule of its leader, Udge. Life in Threerivers continues without change until two young twin brothers, Brudoer and Gamwyn, accidentally initiate events that threaten the established order. The resulting chain of consequences sends Gamwyn on a quest to the far reaches of this postapocalyptic world. Within Threerivers, Brudoer's imprisonment threatens the long-established matriarchal rule of the Pelbar stronghold. "The Fall of the Shell" is the fourth book in the classic series of post-apocalyptic novels about the people of Pelbar. In addition to the Pelbar series, Paul O. Williams's works include "The Man from Far Cloud", "Outside Robins Sing: Selected Haiku", "The Nick of Time: Essays on Haiku Aesthetics", and several other books. Williams is a professor emeritus of English at Principia College and lives in Hayward, California.