A young girl's tricycle gets lost as a French family leaves home for their summer holiday. After becoming accidentally separated from the family, the tricycle is propelled on an unbelievable journey of seemingly unplanned events through the stunning French countryside.

Tomorrow they'll be in Africa, where their father wished to move back ; so today, Mathis and Antoine go to Paris. A day to say goodbye, roam the town, understand homecoming and mainly learn to discover each other...