There seems to be a September in all lives, an autumn of youth and adulthood, a time of tempestuous change when something is dying so that it can be born again. During such a season of life, many amusing situations develop when David Colton, a middle aged sportsman, marries a middle aged artist and designer; for it brings together Colton's son, a prospctive All-American quarterback and his new wife's daughter, a college freshman. The son finds in his new mother a person understanding of his artistic talents which have been suppressed because of his father's athletic ambitions for him. He even considers forsaking football. In resentful retaliation, Father turns to his new daughter who finds in him an ideal teacher for her in her ambitions to be a championship woman golfer. These attachments lead to jealousy and friction that almost dissolve the marriage until Aunt Maud, a lovable old battle-ax who is a sociological writer, sees the situation objectively and amusingly straightens out the misunderstandings. Through the hostile bickerings the boy and girl find themselves and are drawn closer together, and all ends well; for as Aunt Maud contends, "Everyone should be allowed to make a fool of himself at least 'Once in September."