"All Harriet Szász has ever known is life onstage with her twin sister, Josie. As "The Sisters Sweet," they pose as conjoined twins in a vaudeville act conceived of by their ambitious father and managed by their practical mother, who were once theatrical stars in their own rights. Then, in an explosive act, Josie exposes the fraud in a spectacular fashion and runs away to Hollywood. The family retreats to Chicago, where Harriet must figure out how...