When a working girl tries to return a lost fur coat, she gets caught up in a wealthy family's battles.

When millionaire banker J. B. Ball, "The Bull of Broad Street," discovers his wife's purchase of a $58,000 sable coat, he throws it out the window of their Fifth Avenue penthouse and it lands on Mary Smith, ruining her hat. Ball then takes her to a millinery shop and tells her the coat is hers to keep. At work, Ball refuses Mr. Louis Louis' mortgage extension on the Hotel Louis, whose reputation has floundered. When Mary arrives late to work that morning at the publishing office of "The Boys' Constant Companion" wearing a new sable hat and coat, which she claims is only Kolinsky, fake fur, she is fired for questionable morals. Louis, meanwhile, receives word from the milliner that Ball is having an affair and invites Mary to stay at his hotel so she can tell Ball how magnificent it is. Mary accepts unsuspectingly, then goes to the automat with her last dime and meets John Ball, Jr., who has taken a job as a busboy to prove himself to his father. When John causes a riot at the restaurant by opening the food doors so Mary can get a free meal, he is fired. Mary and John then arrive at the Hotel Louis. There, Ball, taking a room because his wife and son have left him, insists on having an elegant dinner sent up to Mary's suite, and she dines with John. The next morning, Wallace Whistling's gossip column tells of Ball's affair, and the Hotel Louis becomes instantly fashionable. When stockbroker E. F. Hulgar comes to Mary's room to get Ball's opinion of the steel market, John jokes that steel will go down, mistakenly causing his father to lose his fortune. The headlines then read that the "Bull of Broad Street" is tottering, and Ball's wife and son return home. When John discloses Mary's leak to the stockbroker, Ball sends the police to find Mary to learn the man's identity. Meanwhile, Mary, realizing her coat is real sable, arrives at the Ball residence to return it, and John and his mother accuse her of being Ball's mistress. John's idea for Mary to reverse the bear market on steel by calling Hulgar saves Ball's fortune, and when Mrs. Ball learns that Mary spent the weekend with John, she is convinced Mary is innocent. Ball hires John as his broker and John gives Mary a job cooking his breakfast.