The first of only two screen appearances by Glenn Miller, this Technicolor musical provides a spectacular setting for the big-band swing. The Glenn Miller Orchestra gets a booking at the Sun Valley resort on the strength of their chance audition with star chanteuse Vivien Dawn (Lynn Bari), who immediately falls for band pianist-arranger Ted Scott (John Payne). The plot thickens when an old and forgotten scheme to promote the band cooked up by manager Nifty Allen (Milton Berle) comes to fruition: Nifty had signed pianist Ted up to be the sponsor of a war orphan, who suddenly arrives at Ellis Island. Unfortunately for Ted, this orphan turns out to be a 17-year-old Norwegian knock-out bent on finding an American husband. Karen Benson (played by international skating champion Sonja Henie) immediately announces she plans on marrying Ted!
Ted tries to off-load Karen onto Nifty's aunt while he, the band and Vivien take off for Sun Valley, but Karen convinces Nifty to sneak her onto the train and when Ted (and Vivien) discover the stowaway in Sun River, trouble ensues!
Mostly a pleasant (if thin) backdrop for terrific Miller tunes such as "It Happened in Sun Valley," the inevitable "In the Mood", and many others, including "Chattanooga Choo Choo" with a superb if somewhat out-of-context dance routine by the Nicholas Brothers and Dorothy Dandridge,