Miss Cleopatra Lewis is about to be launched in society by her aristocratic grandfather. But since she has no intention of marrying, she visits a costume emporium specifically to order unflattering dresses guaranteed to put off any prospective suitors. Jacob Astor Addison is in London, acquiring businesses to add to his theatrical holdings in America--as well as buying an emerald for a young lady back in Boston. He's furious when a she-devil masquerading as an English lady steals Quimby's Costume Emporium from under his nose. Jake strikes a devil's bargain, offering to design her "wallflower wardrobe" and giving Cleo the chance to design his. And somehow in the middle of their lively competition, Jake becomes her closest friend. It isn't until Cleo becomes the toast of all society that Jake realizes she's stolen his fiercely guarded heart.