Young boy Bill Peck adores his father and tries to be good, but the arrival of Bill's cousin Horace upsets Bill's plans. Horace's brattish ways result in Bill rather than Horace getting in trouble.
Bill and his father, Henry Peck, enjoy a day of fishing and then attend the annual fathers and sons banquet, at which Bill wins the first prize for the best composition entitled "My Father." Later that night, they get a telegram stating that Bill's aunt, Lily Clay, who is the sister of Henry's late wife, is coming with her son Horace to live with them. The visitors soon arrive, and the boys immediately dislike one another, as Bill thinks that Horace is a sissy while Horace covets Bill's room. Meanwhile, Lily and Henry discuss the fact that Bill is adopted, which Bill does not know. That afternoon, snooty Horace refuses to play with Bill's friends or join his club, then tells Lily that Bill deliberately excluded him. In response, the overprotective Lily uses insinuations to gradually drive a wedge between Henry and Bill, and their relationship begins to deteriorate. One morning, Bill lets loose a vial of ants into Horace's church clothes, and in retaliation, Horace puts the ants in Henry's clothes, and Bill receives the blame. As further revenge, Horace tells Bill that he came from an orphanage. The same day, Lily fires Duffy, the Pecks' handyman and Bill's buddy. She then throws Bill's things out of his room and installs Horace in it. Meanwhile, Horace hits Bill when the infuriated Bill threatens to sock him for continuing to call him an orphan. Henry refuses to listen to Bill's explanation and punishes him for fighting and for being insolent to Lily. Bill can take no more when he discovers that he has been displaced from his room and runs away to Duffy's shack. Duffy coaxes the boy into going home the next morning to settle things, and upon his return, Bill trounces Horace in a fight. After Henry sees Lily slap Bill, he finally becomes aware of his son's difficulties and sends the unwanted relatives away. Henry then tells Bill the truth about his being adopted, and Bill, realizing how much Henry loves him, happily reconciles with his father.
