Broadway's Gwen Marlowe and Ernest Lane are sweethearts, onstage as stars of Victor Herbert's operetta and offstage as happily marrieds. Then Hollywood beckons, and their fretful stage producer puts the kibosh on any Tinseltown plans by trumping up a romantic triangle that sets the lovebirds feuding. The 24--karat Golden Age singing team of Jeanette MacDonald and Nelson Eddy headlines a lavish, gossamer-weight box office smash glittering with songs that showcase their superb voices. Director W. S. Van Dyke II provides sophistication, the Dorothy Parker-Alan Campbell script provides rapier wit and the Oscar -winning cinematography* provides proof the ravishing, red-haired MacDonald was born for Technicolor .