Ivan Doig, . . Scribner, $25 (371pp) ISBN 978-0-7432-0135-3

In his rambling, sluggishly paced seventh novel, noted western novelist Doig explores the discord that racism sows in the Montana wilderness during the Roaring 20s. Susan Duff, the schoolgirl nightingale from his Montana trilogy's middle book, Dancing at the Rascal Fair, is now in her 40thyear, unmarried, working in Helena giving singing lessons to the upper crust. Her former adulterous lover, the charismatic WWI hero and once gubernatorial hopeful Wes Williamson, reappears and persuades Susan to abandon her other students in order to develop the untrained voice of his African-American chauffeur, Monty Rathbun, with an eye to putting him on the professional stage. Because Monty is black, Susan moves the lessons to the seclusion of her family ranch in mountainous Two Medicine country. But overnight prosperity from oil and copper has brought motorcars and telephones, so secrets are not easily kept. Soon, the KKK makes its presence felt, and Susan's home is vandalized. Though Wes quickly routs the bigots, Monty flees, resurfacing in New York during the Harlem Renaissance, where he attains overnight celebrity as a singer of spirituals. Of course, for black men and adulterous lovers in the 1920s, the course of fame and secret passion is still fraught with peril, and more trouble lies in wait for all. The fine plot is disrupted by frequent flashbacks, paeans to unspoiled landscape, Scottish genealogy and western lore, but those who don't mind digressive storytelling will appreciate yet another Montana saga from one of the state's best-known chroniclers. 11-city author tour. (Oct.)