Young Pascal is away on holiday In Brittany without his best pal Poly. Poly misses her little friend so stows away on a cross country freight train to find him.
A boy takes Poly under his wing and introduces her to his large menagerie of pets. His mum is not so keen to add a horse to the household family roll call though.
Poly arrives at a riding school where a boy called Tony works. The boss of the school plans to return Poly to her home as soon as possible but Tony has now formed a bond with the little horse.
The authorities are now searching for Poly and Tony so he decides to disguise himself. He makes some quick money as a lift operator at a posh hotel. Poly wanders off along a canal side.
Poly becomes locked in the back of a lorry trailer. Tony sneaks into the cab so as not to be left behind but soon has to explain himself when the driver discovers him.
Tony and Poly become parted but are soon reunited again at the Brittany Summer Camp where Pascal has been staying. They have traveled a long way to find Pascal but is he still there?