In Brooklyn, New York, the new kid on the block, fatherless and sweet-natured Remington "Roogie" Rigsby, wants to play baseball, but the other boys reject him, so he and his dog Robbie go home. There, in consolation, his "Grams," Nora Andrews, gives him an autographed photo of deceased Hall of Fame pitcher "Red" O'Malley, who was her sweetheart before she met Mr. Andrews. Later, Roogie tries to bribe his way into playing with the children by offering Andy, their bratty, unofficial leader, all his baseball cards and the photograph. However, Andy double-crosses him by refusing to let him play and when Roogie fights to get his photograph back, it is torn. As he and Robbie dejectedly make their way home, they pass a familiar-looking man in an old-fashioned baseball uniform playing a harmonica. The kindly man stops to chat and predicts that Roogie has the makings of a fine pitcher. When Roogie realizes that he is talking to the deceased Red O'Malley, the man says that things are about to happen for Roogie and sends his regards to Grams. That evening, Roogie discovers that he has grown a bump above the elbow of his pitching arm. The next day, in the alley, Roogie pitches a ball that flies through a cement wall, and then another across the East River, demolishing the chimney of a factory on the other side. Roogie writes Doug Boxi, the manager of the Brooklyn Dodgers baseball team, about his mysterious new skill, but the amused and skeptical Boxi assumes that Roogie's story is a child's fantasy and kindly sends him tickets to a game. Later, at Ebbets Field, during a game that Roogie and Grams attend, a foul ball lands in his lap. He pitches it back with such strength that Roy Campanella, the Dodger catcher, is knocked over. After the game, Roogie is brought to the dugout, where Boxi recognizes him as the author of the letter. The team's "exploitation manager," P. A. Riker, convinces the owner of the team, Barney Davis, that Roogie is "the biggest find since Shirley Temple" and talks him into offering him a contract. Boxi is concerned that the child will be exploited, but Riker offers college money and a big future, and with Boxi's very reluctant consent, Grams and Roogie's mother, Mrs. Rigsby, are convinced to sign. Roogie becomes a national hero and is paid to make product endorsements, which he insists on keeping truthful. At the Rigsby apartment, after seeing Roogie manipulated into making false claims on the air by a dishonest children's show host, Grams and Mrs. Rigsby flatly refuse to allow Roogie to make cross-country personal appearances and endorse peanut butter that promises a bump like Roogie's. Boxi shows up to fire Riker for exploiting Roogie, and then scolds Mrs. Rigsby for permitting it. Realizing that they are kindred spirits, Mrs. Rigsby and Boxi have tea together. Later, though the Dodgers are tied for first place in the league, they fall into a slump, as several of their best players are injured. Because their chance for winning the pennant is at risk, Davis convinces the baseball commissioner to let Roogie pitch the next game, and when Boxi is forced to allow it, he resigns. During the game, the team falls behind, and in the bottom half of the eighth inning, the crowd calls for Roogie. He is put on the mound, and although the bump on his arm feels funny, Roogie pitches his best. However, the batter walks and afterward, in the dugout, the other team members try to console Roogie, who feels that he let them down. In the locker room, Red appears and apologizes to Roogie for exceeding his authority, admitting that things have changed since he played ball. Red concedes that, while he was well-intentioned to want the baseball-loving Roogie look good to the other boys, he now realizes that there is a time and place for everything and that a boy should not be doing a man's job. Although the timing of Red's revelation is inconvenient, Roogie understands, but is still worried about the game. Before disappearing, Red comforts him by saying that there are other kinds of magic, and as Red predicted, the Dodgers win without Roogie's help. Davis, who has learned a lesson, asks Boxi to stay with the team and offers Roogie a position as the team's mascot. When all is settled, Mrs. Rigsby asks Boxi to tea. The following autumn, a man watches as the neighborhood kids exclude Roogie from a football game. After intercepting the ball, he throws it to Roogie, who kicks it over the Brooklyn Bridge. The kids ask Roogie to be on their team, and the man, having finally done his job correctly, reveals himself to be Red, now wearing priestly garb.
