Financier J.B. Ball (Edward Arnold) -- known in the press as "the Bull of Broad Street" -- may be one of the wealthiest investment bankers in the country, but he also knows the value of a dollar. And when his wife (Mary Nash) spends 50,000 of them on a sable coat, he is driven into such a fury in the ensuing argument on the roof of their Fifth Avenue townhouse, that he throws the coat into the street -- where it promptly lands on the head of Mary Smith (Jean Arthur), a clerk-typist on her way to work, riding on the upper deck of a double-decker bus, ruining her hat in the process. She jumps off the bus to try to return the coat, but Ball insists that she keep it. What she really needs, however, is not a 50,000-dollar sable coat so much as a ride to work -- as she doesn't even have a dime for bus fare -- and perhaps a new hat. Ball obliges, taking her to one of the top clothing stores in New York, buying her an expensive fur hat to go with the coat, and then dropping her at work in his limo. Her superiors, seeing her decked out in a sable coat and a new hat, and getting out of the chauffeured car, conclude that Mary is a kept woman, and, therefore, unfit to work for the boys magazine where she is employed, and they fire her. Now out of work and virtually broke, she seems to have become a victim of random fate, but suddenly the scales start to tip the other way from the very same misunderstanding that got her fired. Having been seen in the company of J.B. Ball -- whose name she didn't even get -- she is rumored to be his mistress; the prissy clothing store proprietor (Franklin Pangborn) spreads this story, and that turns Mary into the object of attention for Mr. Louis Louis (Luis Alberni), the owner of a failed luxury hotel on which Ball's bank holds the mortgage, and is about to foreclose. For reasons that she can't begin to understand, since there is nothing going on between her and J.B. Ball (whose name she doesn't even know), or between her and anyone, Louis moves her into the most luxurious suite in his hotel for a dollar a day, asking her only to inform "that certain someone" of how she loves living there. Mary has no idea of who "that certain someone" is, or what Louis is talking about, but she needs a place to live, and Louis is insistent. She still needs to eat, and, while trying to get a meal at the automat, she crosses paths with a handsome, well-meaning, but inept waiter (Ray Milland), who gets fired for helping her. She takes him into her suite so he has a place to stay, and the two fall in love in the course of finding out about each other. She knows that he is John Ball Jr., but doesn't realize that he is the son of J.B. Ball, trying to make it on his own, nor does she yet realize who J.B. Ball is, in terms of being the man who gave her the coat and the new hat, or one of the wealthiest men in the country. But after the elder Ball spends an innocent night at the Hotel Louis, a gossip columnist named "Wallace Whistling" (William Demarest) prints that he is keeping a woman at the hotel, and suddenly the Hotel Louis, perceived as a fashionable playground for the upper-crust, is filled with guests. This multiple case of mistaken identity plunges through two or three new layers, eventually bringing about an impending stock market crash to rival 1929, before Mary discovers who her would-be benefactor and her would-be fiancé are. She bails them out of the jam that they're in, also restoring the Ball's marriage, her own reputation, and her romance with Ball's son in the process.