As they float into the cave on a small inflatable raft with the theme park’s owner Will Stanton in the role of a paddler and narrator, Marshall detects high levels of tachyons. Activating the tachyon amplifier creates an earth-shaking time warp the raft falls into. Having regained their senses in a sandy desert interspersed with items from many eras and discovered that the amplifier is nowhere to be seen, the three travellers rescue an apeman by the name of Chaka, who becomes their friend and guide. They spend the night in a cave where they have taken refuge from a pursuing telepathically endowed tyrannosaur they nickname “Grumpy”, who develops a grudge against Marshall for being intellectually disparaged.