Following a message on Sproggle's radio, the Paradox crew are drawn to the Mountain of Morg on the planet Zark in search of a Lavender Compass, which will lead them to Lavender Castle. On entering the caves of Morg, the crew are unaware of a sinister figure watching their every move who wants the Compass for himself. The caves are full of traps and soon most of the crew are captured. Only Isambard is left. He dodges the traps and comes face to face with the figure: the Guardian. Can Isambard defeat the Guardian and save his friends.