Arco Dorell, [Oscar Tresanini], is a ten-year-old boy living in a bright, cloud-filled future in the year 2932, where people travel through time using rainbow-colored flight suits. He feels left out because his parents and older sister can time travel, while he must wait until he turns twelve. One night, he steals his sister’s time-travel cape and gemstone and secretly aims to slip back into the distant past to witness dinosaurs firsthand.
In the year 2075, Iris, [Margot Ringard Oldra], and her infant brother Peter are watched over by a kind robot caretaker named Mikki, as their parents work in the city. Iris and her neighbor Clifford make their way to school through the rubble of a violent storm, and Iris often steps away to draw. When she spots a rainbow racing across the sky, she follows it to a forest where Arco has crash-landed. Three eccentric brothers—[Vincent Macaigne] as Dougie, [Louis Garrel] as Stewie, and [William Lebghil] as Frankie—are also in pursuit of Arco. Iris initially misdirects them, but they recover Arco’s crystal-like gemstone, and Iris brings Arco to Mikki’s care for healing.
As Arco and Iris grow closer, Arco explains how future humans have moved into the clouds so the Earth can rest, and Iris sketches the platform homes he describes. The three brothers keep tracing Arco, while he admits he cannot fly without the gemstone unless it is both rainy and sunny at once—a rare combination. They hatch a plan to return home by triggering rain with sprinklers on Iris’s roof, allowing Arco to leap away on his rainbow cape. Meanwhile, Mikki, unsure of Arco’s origins and intent, contacts the police in a well-meaning attempt to reunite him with his family.
The group flees to Iris’s school as a massive wildfire lashes the town. Clifford trails them, and the three brothers follow as well, so six youths confront the danger together. Mikki arrives with Peter, but the police robots at the scene refuse to admit them. The six work to outsmart the authorities, and they manage to return the gemstone to Arco. He climbs onto the school roof to fly home, but Iris pleads to come along. As the wildfire intensifies, a protective bubble barrier forms around the school and Arco climbs its exterior wall. Clifford helps Iris slip out just before the barrier seals.
Despite Iris’s plea, Arco agrees to take her with him, but their combined weight causes a crash in the forest as the wildfire rages on. Mikki, carrying Peter, follows the rainbow trail to find them unconscious among the trees. They take shelter in a cave, where Iris awakens to a surreal memory-scape: Mikki carves scenes of her family’s life, including Iris and Arco soaring together on a rainbow, onto the cave walls. Mikki’s effort slowly falters and he warns Iris to leave him and go.
Emerging back into the open air, Iris, Arco, and Peter see a cascade of rainbows descend from the sky, as Arco’s family finally appears. Arco’s parents are older now, and his sister has grown into an adult. They explain they have spent their lives traversing time to find him, and they have located him thanks to the cave-art Mikki left behind. Iris and Arco bid farewell as Arco departs with his family. The story closes with a hint of Iris’s own future: she becomes an architect who designs the cloud platform homes of the era and even begins to dream up time-travel ideas of her own.
In the end, the film intertwines wonder, belonging, and the courage to bridge two eras, suggesting that memory and imagination can reshape the world, and that a spark of possibility can bloom into a future where time itself feels a little more reachable.
