On a trek through the Oregon rainforest, Lassie and her master discover a careless camper who has leaked oil into a stream, endangering hundreds of ducks on their seasonal flight. The Ranger and Lassie teach the camper a conservation lesson he won't soon forget.

Lassie's search for her identity takes her to a wax museum and finally down to the waterfront, where she is befriended by a down-on-his-luck young fisherman with a family and a boat loan he can't pay off.