On his latest expedition, Dr. Rick Marshall is sucked into a space-time vortex alongside his research assistant and a redneck survivalist. In this alternate universe, the trio make friends with a primate named Chaka, their only ally in a world full of dinosaurs and other fantastic creatures. The group encounters a race of lizard men called Sleestaks before meeting the one who sent Marshall the telepathic message, Enik the Altrusian. He explains that he was exiled by the evil Zarn who is attempting to take over Earth with his Sleestak minions, but Enik can prevent this if Marshall retrieves the tachyon amplifier. Meanwhile, Holly learns from a recording left by the long-deceased Zarn that Enik deceived them and is actually the one planning to invade Earth. This is the one and only screen used and matched skeleton of the Altrusian that attempted to stop Enik in the film.