The Demon of Diamond Lake Lassie and the kids have found a family of Black-Footed Ferrets living in the park! These rare animals are endangered and the kids are excited to see their den protected. At the same time, Robert Humphrey has come up with a plan to attract tourists to the park by paying Nick Connelly to impersonate a legendary "Loch Ness" style monster. When Humphrey's plan is more successful than he expects he sets off a stampede of curious tourists that threaten the endangered animals.