A Scottish immigrant on board ship becomes a pawn in a jewel heist aboard the S.S. Cognac, a three-star liner. Blackie Dawson, the uncrowned king of jewel thieves, and his accomplice Pearl Blackstone, have stolen a huge ruby. A detective is searching every cabin, so Blackie forces our young Scot to swallow the gem and, under threat of being shot, to stay mum. The detective is assisted by Flora Danube, a blue-eyed Bulgarian daisy who keeps those eyes open. To escape death, the young Scot disguises himself as a woman, but that draws a lot of attention; when his disguise is discovered, he must climb for his life. Is a European union in the offing?
