Cary Grant stars with Academy Award winner Ginger Rogers in a film shot during World War II, when Hollywood romantic comedy took on the Nazi war machine in Once Upon a Honeymoon. On the eve of World War II, American chorus girl Katie O'Hara (Ginger Rogers) poses as a socialite to lure a wealthy European husband. But she remains unaware that her dashing, wealthy new groom, Baron Von Luber (Walter Slezak), works for the Nazis. Now, as the newlyweds honeymoon on a whirlwind tour of glamorous European capitals, just ahead of the German invasion of each, they are tailed by reporter Pat O'Toole (Cary Grant), who's fooled by neither the bride nor the groom. And as O'Hara realizes her husband's true motives, she finds herself falling in love--and working undercover--with O'Toole.