The squirrel family - from tiny chipmunks to big prairie dogs - is one of the most widespread on Earth. There are almost 300 species of squirrels that can glide through the air, outwit rattlesnakes, and survive the coldest temperatures of any mammal. What is the secret to their success? Uncover the extraordinary abilities of these cheeky nut lovers as a filmmaker puts their problem-solving to the test on a specially designed obstacle course.