Mr. Carter and Guest is the bittersweet story of the pianistic career of Ruth Arnott, a young woman in whom courage contends with caution. That career demands that she abandon her affection for a young farmer, Stu Stacey, who becomes a haunting influence that guides her career to the concert stage. Ruth establishes a liaison with a patricianly business executive, Ransom Carter, who had endured a wretched marriage with a venemous woman and who missed the daughter he did not have. Matthew Foss, Ruth's piano instructor, has mixed feelings for her because she reminds him of the daughter he lost in a ruinous indiscretion. When a condition resembling leukemia strikes Ruth she defiantly carries on. Foss makes amends for his guilt by compelling Ruth, his surrogate daughter, to perform in his place at a crucial concert.