The story unfolds in Sweden during the years 1958 to 1959, centering on Ingemar, a 12-year-old boy who finds himself in the midst of various escapades alongside his beloved dog. As he and his older brother Erik push the limits of their single mother's patience, little do they know that she is battling a terminal illness. To allow their mother the necessary rest and recuperation, the siblings are separated and sent to live with relatives. Ingemar finds himself in a quaint rural town in Småland, under the care of his maternal uncle Gunnar and his wife Ulla, but is heartbroken to leave his dog behind, which is placed in a kennel against his objections.
During his time with Gunnar, Ingemar shares a special bond over the recording of "Far, jag kan inte få upp min kokosnöt" by Povel Ramel. As he navigates this new environment, he encounters an array of intriguing personalities. One of them is Saga, a bold tomboy of his age who shows her interest by sparring with him in the boxing ring. Among the town’s oddities is Fransson, a man obsessed with repairing his roof, and Mr. Arvidsson, an elderly neighbor who enjoys having Ingemar read amusing readings from a lingerie catalog.
When the boys are eventually reunited with their mother, their joy is short-lived, as her health rapidly declines leading to hospitalization. The brothers find themselves under the care of their uncle Sandberg in the city, although his wife suspects that Ingemar is mentally unwell. After the devastating loss of their mother, Ingemar is sent back to Småland.
Upon his return, he discovers that Mr. Arvidsson has passed away, and his uncle and aunt now share their home with a large Greek family. Despite the crowded conditions, Gunnar tries his best to support Ingemar, though it becomes necessary for him to live with Mrs. Arvidsson in a separate residence. Clinging to the hope of being reunited with his dog, Ingemar continuously pesters Gunnar about the dog's fate. Concurrently, tensions arise as both Saga and another girl vie for his affection. During a confrontation between them, Ingemar, in a moment of distress, clings to Saga's leg and begins to bark like a dog. This peculiar behavior leads Saga to react sharply, even proclaiming that Ingemar's dog has been euthanized—a revelation that shatters him, compounded by the grief of his mother's death.
Retreating into Gunnar's one-room "summer house," Ingemar finds solace in isolation, reflecting on his deep sense of loss and a world that appears to be shifting around him. Throughout this journey, he comforts himself with the thought that “it could have been worse,” pondering distressing scenarios like the unfortunate man struck by a javelin at a track meet and the tragic fate of Laika, the first dog sent into space by the Russians.
The film reaches its climax with a live radio broadcast of the iconic heavyweight boxing match between Swede Ingemar Johansson and American Floyd Patterson. As Johansson snatches victory, the whole town erupts in celebration, while the reconciled Ingemar and Saga peacefully sleep together on a couch, wrapped in each other’s embrace.
