Based on a play by Aurania Rouverol, a judge faces blackmail but persuades a small town that his daughter is faithful and his restraining order is valid.
In the small town of Carvel Frank Redman (Charley Grapewin), Hoyt Wells (Selmer Jackson) and others complain to Judge James K. Hardy (Lionel Barrymore) about his restraining order on the aqueduct because of a suit by Nichols. Bill Martin (Allen Vincent) angrily leaves off his wife Joan Hardy (Julie Haydon). Marion Hardy (Cecelia Parker) met William Trent (Eric Linden) on the train home from college. Judge Hardy sees them kiss. Wayne is an engineer and came to work on the aqueduct. Andy Hardy (Mickey Rooney) reluctantly takes Polly Benedict (Margaret Marquis) to a party but finds she has grown up. Oscar Stubbins (Harlan Briggs) calls on Judge Hardy and warns him his career may be over. Joan cries and says she is separated from Bill, who saw her kiss a man at the inn. Her parents comfort her.
Nichols tells Judge Hardy he wants to drop the suit and suggests that the Judge take a bribe too; but Judge Hardy throws him out. By the lake Wayne tells Marion his job is gone, but she defends her father. Wayne ran out of gas and is towed by two drunks until the rope breaks. Relieved after a harrowing drive, Wayne and Marion kiss. Polly tells Andy that her father won't let her go out with him because of his father. Marion and Andy wait for their father, who gives Andy a book to read. Marion complains because of Wayne's lost job, but Judge Hardy says he has a duty to the law. Marion cries, runs out, and finds Joan crying too. Andy reads them the Judge's oath of office.
Redman and Wells tell Judge Hardy they have Marion's story at the inn; but Judge Hardy won't give in, and the story is published. Joan tells her father that she loves Bill and will have his child. Judge Hardy gets a call and goes to get Bill. Mrs. Emily Hardy (Spring Byington) finds a note from her husband to bring Joan to the convention. There Redman nominates someone else for judge, but Oscar nominates Judge Hardy. People ask about his daughter. Judge Hardy tells of blackmail he defied and has Bill deny that he is divorcing Joan. Judge Hardy explains that their water may be diverted by the aqueduct, but he declared the enabling act unconstitutional. Judge Hardy is cheered and re-nominated. He assures Wayne he will get another job. Bill kisses Joan, and Andy kisses Polly.
This successful drama affirming the values of small-town America spawned fifteen sequels about Judge Hardy and his son Andy. Judge Hardy stands for integrity, common sense, and understanding, not just professionally but especially in his family life.