A fast-paced, marvelously detailed account of the exploration of the American West. Biographer Ambrose relies on newly published materials and original journals to recreate the high adventure and politics of late 18th-century America. This best-selling book is rich in details of geography, flora, fauna and Native American life. It is considerably enlivened by many maps -- and the author's own modern journey in the footsteps of Captain Lewis and the Discovery Corps. Ambrose knows how to tell a story and this is a great one.  (USW20, $17.00)