A few days before he is to leave Carvel for Wainwright College, Andy Hardy convinces "Botsy" and his friends to buy his jalopy for twenty dollars. Assuming that his friends will soon pay him, the nearly broke Andy then mails a twenty-dollar check to New York to cover the cost of having his new car driven to Carvel. When his sister Marian states that her boyfriend, Jeff Willis, who has been charged with drunk driving, could drive the car for free if Andy convinced their father, Judge James K. Hardy, to give him a light sentence, Andy pleads Jeff's case. Although the judge suspends Jeff's sentence, he also forbids him from driving for ninety days. Andy's disappointment is soon alleviated when his estranged girl friend, Polly Benedict, calls to make up with him. Before reuniting with Polly at her house, Andy, an incorrigible flirt, asks Marian for advice on how to "make girls crazy about him" without the promise of fidelity. Following Marian's suggestions, Andy plays the "cool cookie" with Polly, who appears to fall for the tactic but is really plotting with her college-aged friend, Sheila Brooks, to teach Andy a lesson. While Polly remains indoors, Andy goes for a swim in the Benedicts' new pool and meets the sophisticated Sheila. After explaining that she is a psychology major doing research on "reflexes," Sheila surprises Andy with a kiss. She kisses him again underwater, then tells him that he will be considered a "panty waist" if his father accompanies him to Wainwright, as the judge has planned. Later, at home, Andy hints to his father that returning to Wainwright, his alma mater, might prove a disappointment, but the judge is too preoccupied with a case involving a young boy named "Tooky" Stedman to notice. To help his father, Andy visits Tooky, who crashed into a lumber truck while coasting down a hill in his wagon and is now suing the lumber company for failing to place a red flag on the truck's load. Although Andy agrees with his father that Tooky would not have been able to see a flag, and therefore could not have avoided the accident, he tells the judge that, unless Mrs. Stedman, a widow, wins the case, her house will be repossessed in two weeks because of Tooky's medical bills. Thus apprised, the judge, who postponed ruling on the Stedman case for two weeks so that he could go to Wainwright, cancels his plans, much to Andy's relief. Andy's troubles soon return, however, when Botsy and his friends, who have yet to pay Andy, crash his jalopy into a store window. Botsy and the boys, who have been ordered to replace the window, blackmail their way out of giving Andy his twenty dollars using a photograph that Botsy took of Andy ironing Marian's underwear. Now concerned that his check will bounce, Andy questions Polly, whose father George is president of Carvel's bank, about how much George likes him. Seeing an opportunity to further tease Andy, Polly "interprets" his queries about her father as a marriage proposal and "accepts." Sheila then twists Andy's flirtations into a proposal, and Andy leaves Polly's convinced that he has promised himself to two different women. Early the next morning, just before he is to leave for college, the still dazed Andy is summoned to the Benedict house by George. Sure that George wants to discuss his marriage to Polly, Andy reluctantly appears, and is overjoyed when George instead presents him with a new checking account, into which the judge has already deposited an allowance. Andy then is confronted by Polly and Sheila, who play an incriminating recording of him wooing them with the same lines. Feeling that Andy has finally learned his lesson, Polly and Sheila assure him that he is not engaged and agree to write to him at Wainwright. Moments later, Andy bumps into Jeff, who casually reveals that while he was riding a bike, he noticed a "no trucks" sign on the hill on which Tooky had his accident. Armed with this information, Andy rushes to the courthouse, where his father is about to pass judgment in the Stedman case, and the Stedmans are awarded their settlement. After the judge declares that he will be going to Wainwright after all, Andy, acting on advice from his mother Emily, levels with his father that he does not want him to go. Although the judge at first bristles, he finally understands that he is intruding on Andy's special day. Andy, who has learned that he cannot use his newly acquired car on campus, has already left for the train station, and as his parents are driving to meet him there, one of their tires blows. Using Tooky's wagon, the judge improvises a repair and they arrive at the station seconds before Andy's train pulls out. After a heartfelt goodbye, Andy boards the train and happily discovers that a pretty young woman seated near him is going to be one of Wainwright's first co-eds.