Now accompanied by Lassie, Ron and Dale have the gold they have been placer mining assayed--and just for the heck of it, buy an old treasure map and go in search of a gold mine. Once they find the place, however, their search is endangered by fire heading for some old dynamite left in a shed.

Ron and Dale, home from college, go out on the annual stray roundup and make a bet on which of them will find the most cattle. But it's Lassie who gets the jump on them, helps a calf stuck in quicksand, and then must help Ron when he's thrown from his horse.

Ron and Dale, spending two days camping at Pine Lake before returning to college, pick up a boy that Dale can tell is ""on the run."" Sure enough, once he leaves them he builds a campsite in the woods. When the boys find his camp in the woods, he steals one of the motorcycles they've rented.