Another Permian adventure awaits when Tom, Jamie and Wanna discover a friendly pareiasaurus. The enormous herbivore and Wanna soon become friends, but suddenly a hungry anteosaurus appears on the scene and he's looking for some dinner! It's up to the boys to set a trap for the predator and try and lead their new friend to safety. But how will they ever get the pareiasaurus across the muddy swamp without him sinking?