Giovanni is a young, bluish-colored cat whose father is away on a fishing trip and whose Giovanni's Mother is ill at home. In class, during a lesson about the Milky Way, the teacher asks what the galaxy is made of. [Giovanni] knows it’s made of stars, but he can’t summon the words, so his classmate Campanella steps in to shield him from the teasing. After school, the day continues with ordinary chores: Giovanni works a typesetting job at a local print shop, buys a loaf of bread and some sugar, and returns home to find that no milk was delivered. A quick trip to the dairy reveals an elderly cat who tells him to return later, hinting at the small delays that color the town’s rhythms.
That night, the Centaurus Festival—the Festival of Stars—lights up the town with a hush of anticipation. At the celebration, Giovanni endures taunts from classmates who doubt his wishes of an otter-skin coat from his father. He climbs to the hill at the town’s edge, gazing upward as the sky unfolds in dark velvet and pinpoints of light. A steam train unexpectedly materializes on the night tracks, and Giovanni steps aboard. On the train, he is joined by Campanella, and together they witness a surreal parade of landscapes slipping by the windows: fields of blossoms spreading like a living painting as the wheels hum a distant music.
The train makes a stop at a quiet overlook where they alight and follow a sign toward The Pliocene Coast, where their teacher leads an excavation of fossils from crystalline sands. After the break, they slip back onto the train and meet a bird-catcher who traps herons and transforms the birds into candy, a curious magic that blends wonder with whimsy. The two boys assist a blind wireless operator tending a radio system. From the operator’s equipment, a transmission emerges, recognized by an elderly passenger as a hymn—“Nearer, My God, to Thee”—a haunting note that echoes through the car.
A ticket inspector appears, and Giovanni discovers a rare ticket tucked in his pocket, a key that lets him travel anywhere the train runs. The group is joined by a tutor and two children, and they share apples as they glide past a vast cornfield where the sound of the “New World Symphony” drifts through the air. As the train glides past the Scorpius region, one of the children recounts a tale of a scorpion who perished in a well after escaping a weasel; the scorpion’s restless spirit is said to have burned bright in the night sky, a symbol of future happiness for others.
When the train reaches the Southern Cross, every passenger except Giovanni and Campanella steps off to enter what is described as Christian Heaven. Campanella promises to continue the journey with Giovanni forever, but the moment arrives when Campanella spots what he calls the true Heaven—the place where his mother waits—and he departs the train, vanishing from the car.
Giovanni awakens back on the hilltop, the world returning to its ordinary brightness. He makes his way to the dairy again to collect a bottle of milk, and on the walk home he learns that Campanella has fallen into a river while saving Zanelli, a classmate, from drowning. Campanella’s father, Gorô Naya, has given up the frantic search, and a letter from Campanella’s father arrives, promising to come home soon. Back in the quietness of the town, Giovanni believes that Campanella is “at the edge of the universe,” a place they explored together, and he vows to live as the scorpion did—bringing happiness to others—before he continues his journey toward home, carrying the memory of their shared voyage into the night.
