In Benjamin Percy's new thriller, a post-apocalyptic reimagining of the Lewis and Clark saga, a super flu and nuclear fallout have made a husk of the world we know. A few humans carry on, living in outposts such as the Sanctuary-the remains of St. Louis-a shielded community that owes its survival to its militant defense and fear-mongering leaders. Then a rider comes from the wasteland beyond its walls. She reports on the outside world: west of the Cascades, rain falls, crops grow, civilization thrives. But there is danger too: the rising power of an army that pillages and enslaves every community they happen upon. Against the wishes of the Sanctuary, a small group sets out in secrecy. Led by Lewis Meriwether and Mina Clark, they hope to expand their infant nation, and to reunite the States.