Barney has found a wonderful place to play - the chalk-pit or rubbish dump near his granny's home. One day the ground gives way and Barney finds himself in a cave in the middle of the dump, and that's where he meets Stig. Stig is living wild and has a lot to learn from Barney, but equally he has a lot to teach him. They soon become friends, discover each other's ways and embark on a series of extraordinary adventures.