Harriet isn't just strong - she's the strongest girl in the whole world! And though her super-strength is mostly wonderful, it does make things like bouncing on trampolines, mixing cake batter and putting the cap on the toothpaste a bit, well - tricky. So when the Seriously Strong Touring Circus comes to town, Harriet thinks she might POP with excitement to see other people just like her! Hans the Hairy and Betty Biceps show her that being strong should be celebrated - and when Muscleman Max prepares to break a world record, Harriet suddenly finds herself taking a starring role in the performance.