Rhythm on the range: Bing Crosby plays a champion rodeo rider who discovers a runaway heiress hiding out in his boxcar heading out West. Includes the song 'I'm an old cowhand'. Rhythm on the river: The story of a composer of hit songs who is in demand by the people who produce musical shows. His work is actually done by ghostwriters (Crosby and Martin) who try to break loose on their own.