영국 요크셔 지방에서 광부로 일하던 아버지가 가족의 사랑을 받던 개 래시를 백작에게 팔고, 스코틀랜드로 옮겨진 래시가 극적으로 탈출에 성공해 가족에게 돌아오기까지의 과정을 그린 가족영화.

Hard times come for the Carraclough family and they are forced to sell their dog, Lassie, to the rich Duke of Rudling. Lassie, however, is unwilling to remain apart from young Carraclough son Joe and sets out on a long and dangerous journey to rejoin him.

Shell-shocked Barbara must face up to the loss of a dear companion after a tragic accident. Her best friend Klara and husband Torsten devise a plan to thaw Barbara's heart, after she reminisces about the incident, the funeral, and happier times. Will she agree to the suggestions of her nearest and dearest? Can grief turn into hope?

The story of the rough collie hero, Sunnybank Lad.