Supervillains do not merely play hooky. True, coming back to school after a month spent fighting - and defeating - adult superheroes is a bit of a comedown for the Inscrutable Machine. When offered the chance to skip school in the most dramatic way possible, Penelope Akk can't resist. With the help of a giant spider and mysterious red goo, she builds a spaceship and flies to Jupiter. Mutant goats. Secret human colonies. A war between three alien races with humanity as the prize. Robot overlords and evil plots. Penny and her friends find all this and more on Jupiter's moons, but what they don't find are any heroes to save the day. Fortunately, they have an angry eleven year old and a whole lot of mad science...