Geronimo Stilton Space mice #1: Alien Escape is the first book in the spin-off series of the wildly successful Geronimo Stilton series. Intended for the same audience as that of the original series, children of 6-12 years of age, this book introduces a Geronimo Stilton from a parallel universe. Geronimo Stilton is the captain of the spaceship Mouse Star 1 which he uses to fly through the cosmos.