At first Chitty-Chitty-Bang-Bang is just a big and powerful car, but as the book progresses the car surprises the family by beginning to exhibit independent actions. This first happens while the family is caught in a traffic jam on their way to the beach for a picnic. The car suddenly instructs Commander Pott to pull a switch which causes Chitty-Chitty-Bang-Bang to sprout wings and take flight over the stopped cars on the road. Commander Pott flies them to Goodwin Sands in the English Channel where the family picnics, swims, and sleeps. While the family naps, the tide comes in threatening to drown them. Chitty-Chitty-Bang-Bang wakes them just in time with a hiss of steam. At the car's direction, Commander Pott pulls another switch which causes it to transform into a hovercraft-like vehicle. They make for the French coast and land on a beach near Calais. They explore along the beach and find a cave boobytrapped with some devices intended to scare off intruders. At the back of the cave is a store of armaments and explosives. The family detonates the cache of explosives and flees the cave.