At the turn of the century, New York dentist Biff Grimes tries to start a new practice after spending a year in prison. One Sunday afternoon, while reminiscing about his old neighborhood with his friend, Nick, the barber, Biff receives an emergency call to pull alderman Hugo Barnstead's aching tooth. Biff carries a grudge against Hugo, a man he has known since his youth, and while picturing his revenge, agrees to help him. Biff's rivalry with Hugo began years earlier when both men were in love with beautiful Virginia Brush: One day, Hugo drives up in a new car and invites Biff to go riding with him, Virginia and her friend, Amy Lind. Hugo lures Biff into accompanying him by promising him that he can be Virginia's date, but when they join the women in the park, Hugo pairs off with Virginia. After the car gets a flat tire, Hugo asks Biff to change it and goes off with Virginia. Amy, a nurse who is outspoken in favor of women's rights, shocks Biff when she announces that marriage is an "outmoded, silly convention." Later, on the drive home, the car startles some horses, and because Biff is at the wheel, Hugo allows him to take the blame. Later, Hugo and Biff take Amy and Virginia on a charity boat ride, but this time, Biff insists on dancing with Virginia, who gives him a flirtatious kiss. Believing that she is in love with him, Biff asks her for a date. Virginia sets a time far in the future and gives him another little kiss to seal the arrangement. On the day of their date, Biff waits in the park with a diamond ring, but instead of Virginia, a dressed-up Amy meets him. When Biff learns from a passing friend that Virginia and Hugo married earlier that day, Amy does her best to console him, revealing that she is not as much of a free-thinker as she pretended to be. Eventually, Biff asks Amy if he can see her again, and over time, they fall in love and marry. Several years later, Biff accidentally meets Virginia, who invites him and Amy to dinner. Hugo ostentatiously displays their wealth and then offers to bring Biff into his construction company. Biff accepts his offer, but is frustrated when he learns that he is not expected to do much except sign his name to various papers. The reason for this becomes clear when one of Hugo's buildings collapses. Because his is the only name on the papers, Biff is sent to jail, while Hugo goes free. When he is released on New Year's Eve, 1899, having completed his correspondence school lessons in dentistry, Amy is waiting, and a humbled Biff vows that from now on he will be plain Biff Grimes, dentist. Remembering these events, Biff plots his revenge. When Hugo and Virginia arrive, they are quarreling, and Biff sees that they have a miserable marriage. Biff pulls Hugo's tooth without an anesthetic and, greatly cheered, tells Amy how much he loves her. She then whispers to him that she is pregnant.
