Mr. Rattigan has given a mild wartime slant to his play. One the eve of his marriage, the young and wealthy Earl of Harpenden puts up an American Lieutenant for the night; and in the morning dates him up with a former girl friend. The American mistakes the earl's finance for the girl friend, and the two of them fall in love with each other before he discovers his mistake. What with a French officer also in the race, the girl friend very much in evidence, and the fiancee's father, a deadbeat duke, adding to the complications, an evening of hilarious fun is the result.