John is a cheerful and energetic young boy, who lives in a small coal-mining town in England. One day he finds a small dog lost in a flock of sheep. John takes her back home and names the puppy Lassie. Soon they become good friends, just like real siblings. Lassie is a very lovely and smart dog, so everyone in the town loves her very much.
But their happy life doesn't last long. Suddenly a coal-mine owner closes his company because there is no more coal left in the coal mine. John goes to meet the coal-mine owner to request a further investigation. The owner accepts John's request, but in exchange for that, he takes Lassie to Scotland.