Onlee One has escaped from the Planet Pen, only to find himself on another mysterious planet - Libera! Here Kats and Muss seem to live in perfect harmony, and here is where Onlee One finds his long-lost father, Pale One. Onlee One is overjoyed, but now he needs his father's help to carry on the fight against the deadly Dark Claw . . . and another enemy who is waiting in the wings . . .