At the family breakfast table, young Denny Reed annoys his parents and grandfather Joshua with his unpleasant attitude and preoccupation with earning money to buy a new bicycle. Denny goes out with his younger friend Binks to distribute leaflets for a local storekeeper, and protects the little boy from a local bully. When Denny notices Grandpa returning from the store, he instructs Binks to finish distributing the leaflets so that he can bring the groceries home himself and collect a nickel. With Denny gone, Binks throws the leaflets down the sewer. Denny and Grandpa are walking home when the bully returns with his friends, and a fight ensues. As Denny approaches his home, he sees the bully's mother complaining to Mother Reed about Denny's supposed attack on her son. Mother angrily strikes Denny, and the boy runs off. Mother calls Father Reed at work, where he is talking with a policeman sent by the storekeeper whose flyers were discarded. When Grandpa offers to look for Denny, the distraught Mother lashes out at him cruelly. Stung, Grandpa goes to the attic for his suitcase, and when he finds his old diary inside, remembers his own childhood: In 1892, young Josh is writing in his diary late at night when his spoiled little sister Ruthie begins screaming from her room that he is bothering her. Josh's strict, rather cold father punishes the boy by telling him he will not receive the toboggan he was promised for his birthday. Father returns to bed, and Mother gently suggests that he is too hard on Josh, who is afraid of him. On Josh's twelfth birthday, Father sits the boy down for a talk and says he should plan to go to college and prepare for a secure future. Father adds that one's choice of friends is important, which is why he has forbidden Josh to associate with Johnny "Duckface" Kelly, who has a hard life with his coarse, drunken mother. As Josh prepares for bed, Duckface whistles to him from outside, and Josh nervously sneaks out to meet him. Josh brings his friend a piece of his birthday cake, and is shocked to see that Duckface bears bruises from his mother's recent rampage. Just then, Father appears and Duckface runs off. Father beats Josh, and the boy bitterly writes in his diary that he is now certain that his father hates him. Later, Carp's Colossal Circus comes to town, and Josh and Duckface are hired to do menial work in exchange for free tickets. One day, Bobo the clown becomes ill before a performance, and after examining him, the circus veterinarian orders him to rest. Bobo decides to perform anyway, and Josh and Duckface watch proudly as the clown goes through his slapstick antics. In the middle of Bobo's act, the veterinarian rushes in to tell Carp that Bobo has typhoid fever, but the mercenary Carp refuses to stop the show. When Bobo collapses during a stunt and dies of a broken neck, word of the disease begins to spread among the circus employees, and they begin dismantling the tents and packing up. Duckface proposes that they leave town with the circus, and Josh goes home to pack his bags. Before he can sneak out, however, Josh comes down with the fever. In the face of his son's illness, Father's stern exterior cracks, and he at last begins to treat Josh with warmth and affection. One night, Josh takes a turn for the worse, and Father heads out in the rain to find Dr. Bailey. As he leaves his house, Father is approached by Mrs. Kelly, who says that Duckface is missing. Father tracks the doctor down at the circus caravan, where Carp lies dying. One of the workers comes in with Duckface, who was found hidden in one of the wagons, and Dr. Bailey pronounces the boy dead. Taking Duckface's forlorn dog and Dr. Bailey with him, Father returns home. Dr. Bailey gives Josh a sedative, and in the morning, the boy's fever has broken. Josh drifts into happy dreams about things he will do with his father when he is better. When Josh awakens, however, his mother sadly tells him that Father has died from the fever. After several months of mourning, Josh makes the final entry in his diary: "When people love other people, why don't they show it or something before it's too late?" Back in the present, Grandpa looks at the words he wrote nearly sixty years earlier and wipes away a tear. Downstairs, the Reeds are arguing about child-rearing when Denny comes home and locks himself in his room. Late that night, Denny begins to pack a suitcase and finds Grandpa's diary inside. Fascinated, Denny immediately sits down and begins reading. In the morning, Denny apologizes to his mother and tells his father he will use his bicycle money to pay for the leaflets. He then goes into the kitchen, where Grandpa, still hurt by Mother's outburst, is eating alone. Without a word, Denny embraces the old man and brings him to the dining room table, where Father respectfully pulls a chair out for him. Denny asks Grandpa to go fishing with him, and they happily head off to the fishing hole.