Great-uncle Lancelot is an extraordinary man with a huge white beard and a walrus moustache. When he builds a fantastic flying machine, powered by tree sap, lit by electric eels and heated by solar panels, his niece and nephews have never seen anything like it. Then, in search of his lost brother, Perceval, he whisks the children off in his flying home, to set out on an amazing journey around the world.

Lancelot's remarkable knowledge and the special powers he gives the children enable them to watch and talk to some incredible creatures.

On their journey they discover all sorts of fascinating things about animals, such as how snakes move and how swallows migrate.

Of course, they encounter many dangers along the way – in Africa the plucky explorers are caught in a sandstorm and Lancelot is chased by an angry rhino. And throughout their journey, one question remains. Will they ever find Perceval?