Microbe is a timid child, often immersed in drawing. Gasoil, an inventive and cheeky boy, winds up in Microbe's class in the middle of the year. A close friendship immediately forms between them.
As summer vacation approaches, the two friends have no desire to spend two months with their families. Making use of a lawn mower and a few planks of wood, they build their own "car" and set off to travel through France...