In the finale of the "Shoestrings" series, Kyle and his grandfather Caleb must return to the time of the comet striking the earth one more time. Caleb teaches his young grandson things about the universe and time travel that have shocking implications. Grandfather and have the adventure of a lifetime, literally, as they explore one again the land of the dinosaurs while hoping the visit will change the disaster that occurred the last time Kyle, Teresa and Sonja visited.