Indian customs and some hydrophobic wolves offer the best moments in this historical novel. It attempts to suggest an answer to the mystery of who was the boatman, Francois Rivet, who went along with the Lewis and Clark Expedition and then disappeared midway through the journey? The question allows the author to recount the progress of the expedition from a fresh point of view, Rivet's own. In 1804 young Frank rivet falls in with Lewis and Clark, who are going up the Missouri in search of the Northwest Passage, a path by water across the huge new Louisiana Territory. Frank, half-Pawnee, is also looking for his white father. There is a close call with the Teton Sioux, and in Mandan town, both Frank and Captain Clark are smitten with a pregnant 16-year-old Shoshone squaw, Sacajawea, wife of an old French trader. She is instantly taken with Clark. Later, among the Shoshones, Frank finds his father, prematurely aged, deranged, and guardian of the tribe's children. Frank deserts to go live with Sacajawea and her old husband, hoping eventually to buy her from him. Stilted mock-French idiom clogs the action, sometimes clearing with excellent lyric passages.