When Sarah airlifts a wolf and her pups to another park for their own safety, Zoe discovers that one pup has been inadvertently left behind. Promising the tiny wolf that she will return it to its mother, Zoe, Lassie and Harvey begin to hike the pup out of the backcountry. The little wolf turns out to be a handful... and when it escapes from the kids, Lassie must face a mountain lion to protect the kids as they try to retrieve the cub.
