Post-disaster odyssey from the author of Ancient Shores (1996), etc. Far-future Earth is littered with decaying monumental structures built by the mysterious Roadmakers, who, according to tradition, succumbed to a lethal plague. Now, the Mississippi-based republic of Illyria has developed an early-medieval technology where, none too believably, firearms arc crafted but steam engines and printing presses are unknown. Of an expedition sent to locate Haven, the fabled repository of Roadmaker technology and artifacts, only Karik Endine returned--and he had nothing to say of his journey or what he found. After Karik drowns himself, bequeathing to young silversmith Chaka Milana the only known copy of a Mark Twain novel, the question remains: Where did Karik get the book? So Chaka organizes her own quest, including scholar Silas Glote, Karik's son Flojian, woodsman Jon Shannon, soldier Quait Esterhok, and former priestess Avila Kap. On their journey, far to the northeast, they will encounter vast ruined cities, flying trains, bandits, still-functioning computers, slavers, reclusive engineers, and crazy old balloonists; three travelers will die before the survivors reach Haven to discover the fate of the previous expedition and the source of Karik's mystifying book. Solid characters and a consistently intriguing plot (though McDevitt's grasp of the details isn't always secure): an uplifting tale (cf. David Brin's The Postman), well up to previous standards.