After the death of his mother, eleven-year-old Josh goes to live with his uncle, Calum, who has a farm on a remote island. Uprooted and lonely, Josh finds solace in his love of animals. So one day, when he finds a tiny Border collie pup left to drown in the river, he decides to rescue it and keep it as his own. But money is scarce and a dog that can't earn her keep would not be welcome by Calum, and Josh must raise his new friend, Reggae, in secret.

As the pup grows and demands more attention, Josh's schoolwork suffers, despite the help of the local vet's daughter, Yvonne. Josh must decide as well what to do with Raggae - he cannot keep her hidden forever - and decides that he will train her for the local sheepdog trials. But the training is tough and time-consuming. Can Josh and Reggae bring it off in time? All is going well until someone discovers Josh's secret and will stop at nothing to ruin their chances ...