When popular novelist Josephine Evans suddenly drops from sight during a lecture tour and then telephones her New York literary agent, Adam Trent, to announce that she is canceling the tour, Adam frantically summons Jo's children, Jeff and Susan. Guessing that their mother has fallen in love, worldy adolescents Jeff and Susan track her to Digby, Pennsylvania, the college town in which she gave her last lecture. As predicted, Jo confesses that she has fallen in love with chemistry professor Michael Kingsley, but stuns her children when she reveals that she has married him. Susan and Jeff reluctantly move in to their stepfather's stuffy house and their introduction to him is awkward and painful, as Michael is as dull and provincial as they are fun-loving and sophisticated. When Michael proclaims that his wife will not be resuming her writing career, Jo, Jeff and Susan all protest. Jeff and Susan are so incensed by Michael's conservative attitudes that they vow to break up the marriage, even after Michael makes a sincere, if ungainly, attempt at ingratiating himself with them. While agreeing to enroll at Digby, Jeff and Susan sweetly advise Michael to read Jo's last novel, As I Knew Paris , knowing that he will be scandalized by it. Jeff and Susan then begin classes at Digby, and Susan is immediately smitten with her theater professor, Tom Farrell. After she makes a bet with some co-eds that she can secure a date with Tom, even though dating professors is against Digby policy, Susan rattles Tom by revealing that she knows more about his lecture topic than he. Susan then hints that she has highly personal information about the next playwright on Tom's reading list, and Tom, anxious to avoid more humiliation, invites her to dinner that night. Later, Susan and Jeff drop by Michael's chemistry lab and, as he pours over As I Knew Paris , casually tell him that the book's most decadent female characters are based on Jo. Once alone, Michael envisions Jo entertaining men in Paris and, consumed with jealousy, rushes to the local book store and buys all of its copies of As I Knew Paris . Upon returning home, Michael first finds Jo having tea with Pepe, a French delivery boy, then discovers Tom at the door. After chasing the confused Tom away, Michael angrily announces that he is eating out. Susan catches up with Tom and sneaks into his apartment, where she regales him with stories about her mother's literary friends. Susan then reads a script that Tom has just finished and offers to help him rewrite it with more believable characters. Jo, meanwhile, questions Michael about his odd behavior, and he coldly admits that he finds her novels "cheap." Later, Jeff and Susan, who have wired Adam, advance their plot by advising Michael not to attend an upcoming chemistry conference in Philadelphia, as Jo will be on her own. Though concerned, Michael decides to go anyway, but as his train is pulling out, he sees Adam, who has just arrived from New York, give Jo a warm kiss. Panicked, Michael disembarks at the first stop and returns home, only to discover that Adam has moved in and is escorting Jo and the children to an off-limits roadhouse. There, the teetotaling Michael insists on engaging Adam in a drinking contest. Although Michael has bet that he can out-last Adam because of his superior body chemistry, seasoned drinker Adam remains sober, while Michael ends up drunk and playing the bass with the club band. The next day in class, a hung-over Michael is teased by his students and is reprimanded by the dean. Susan, meanwhile, is having second thoughts about continuing the plot, as she realizes that she has fallen in love with Tom. To keep his sister in line, Jeff drops by to see Tom and tells him that the women in As I Knew Paris are modeled after Susan. Later, a fed-up Michael throws both Pepe and Adam out of his house, then reveals to Jo that "her weakness" almost cost him his job. When Michael demands that Jo change her ways, Jo decries him for not trusting her and packs for New York. Susan then storms home, furious at Jeff because Tom has rejected her. A week later, however, Tom comes by the Kingsley home and tells Susan that he loves her, past or no past, and the two reconcile. Susan and a repentant Jeff then conspire to reunite Michael with Jo, who has just filed for divorce. Posing as scared, young children, Jeff and Susan convince the judge in the case to deny Jo and Michael a divorce. Although confused by the judge's harsh comments, Jo and Michael forgive each other in court and reunite. When they finally deduce what their children have done, Jo and Michael chase them around the courthouse and give them a good spanking. Susan and Tom then reveal that they, too, are newlyweds.