To test his wife's faithfulness, the jealous husband of a musical comedy duo impersonates a Russian officer and proceeds to court her in The Chocolate Soldier. Karl Lang (Nelson Eddy--Knickerbocker Holiday, Rosalie) and Maria Lanyi (Risë Stevens) are the musical toast of Vienna. Karl has fame, fortune, success, a beautiful wife... and suspicions. But his ruse to test her loyalty proves a frustrating experience when she keeps him in constant emotional turmoil by alternately accepting and rejecting his advances. Finally, deciding his real self is losing the battle for her affections, Karl drops the dual role... but there are still more surprises in store for him in this romantic musical comedy.