The New Adventures of Lassie

Humphrey's niece, Samantha, brings a group of girls up from the city for her birthday party, she and Zoe don't get along. When Samantha's choice of skating ponds puts her whole group in danger, Zoe intercedes, saving Samantha and finding a true ally - which is a good thing, because it's going to take both of them together with Lassie to save Harvey's life.