Lassie has settled in living with Cully-and mostly occupied keeping Cully's mischievous Yorkshire terrier Silky in line-when the elderly man suffers another heart attack. Lassie fetches Doc Weaver, but in the process of his getting Cully to the hospital, Silky escapes, fair game for tourists at a tourist camp.
Corey is sickened while surveying in Echo Canyon, and closes the forest 48 hours before the opening of tourist season. Facing the ire of the mayor and other local businessmen of the area, he searches for the source of the problem, which he is sure is in the water supply. He's right-and Lassie has ingested some of the poison.
When a bear raids food from campers at the Twin Oaks campground, Corey helps the local game warden relocate the animal to an area away from tourists, not knowing the bear left a cub behind-luckily Lassie has found the little fellow and is leading him to safety, fighting off a bobcat and hawk to do so.
When trees cut from the forest for a Christmas charity project are stolen from a church lot, Stuart plays on the suspected thieves consciences by introducing them to the charity givers and recipients .