This time, Jett's mission takes him to the Swiss Alps. A girl named Lena has ordered a barrel for her St. Bernard Biggie, a prospective rescue dog. Lena's father, however, thinks that he is far too young for this. But shortly afterward, Biggie can prove that she has what it takes to be a rescue dog. The train that is supposed to take Jett, Lena, and Biggie to the mountain station suddenly derails.
