Part I
Deep within Bigsir National Forest, a large amber monolith, thought to contain the remains of a dinosaur, is found. It is transported to the San Francisco museum where it is to be unveiled and studied by the Earth Corps, a government funded research team dedicated to investigating mysterious events under the Earth’s surface. Elsewhere, a man named Blackthorne Shore is running an oil drilling operation, and releases the Inhumanoid Tendril, which was his main intention anyway. Meanwhile, back at the museum’s unveiling ceremony, the monolith begins to emit a high-pitched shrieking sound, partially shattering it and revealing the Inhumanoid D. Compose’s head. As the people in the museum flee outside, Tendril, drawn by D. Compose’s screams, approaches the museum destroying everything in his path. The Earth Corps change into their protective exo-suits, while Dr. Derek Bright runs a scan on the Tendril monster. He determines that it is plant-like, and Auger goes to get a tissue sample while Tendril is being distracted by the police helicopters that are attacking him. Tendril finally manages to reach D. Compose, and frees him from the amber. They then disappear within the smoke created by the various attempts that are being made to stop them. Afterwards, Auger and Herc Armstrong go to the San Francisco bay, thinking it may be where the Inhumanoids escaped to. Dr. Bright goes to the oil-drilling shaft where Tendril was reported to have came from, and discovers the cell where Tendril was contained. Liquidator goes back to the forest where D. Compose was found, and discovers the Redwoods, a race of living trees who were disguised as tree stumps. At first they intend to kill him, but from his aura, they realize he doesn’t mean them any harm. They tell him the story of the ancient war between the Inhumanoids and the Mutores that took place below the surface of the Earth. Although their losses were great, the Redwoods, along with the Granites, a race of living rock people, and the magnetic Magnokor, eventually defeated the Inhumanoids and drove them into submission. Tendril had been imprisoned within a stone chamber, D. Compose had been paralyzed by sunlight and fell into an amber pit, and the tyrant Metlar was trapped within Magnokor's magnetic field. The Redwoods tell Liquidator that since Tendril and D. Compose are now free, they will try to release the remaining Inhumanoid, Metlar. Meanwhile, during their exploration of the bay, Herc and Auger find giant footprints on the sea-floor that lead to a large underwater cave. They enter it and are ambushed by Tendril and D. Compose, but manage to escape. Later, when they all meet back at Earth Corps headquarters, they each report their findings, and determine that they have to stop the Inhumanoids before they can release their Metlar. At that moment, one of Tendril's tentacles crashes through the floor.
Part II
The Earth Corps manage to drive Tendril back into the earth, leaving their headquarters destroyed. They decide to follow Tendril’s trail into the Earth to find Metlar. Meanwhile, Blackthorne is trying to have Senator Masterson cut the Earth Corps budget, when Sandra walks in and finds out he had deliberately set the Inhumanoids free. After she leaves in disgrace, he tries to have his guards stop her, but she gets away. He then has the Senator give him the plans for the Earth Corps technology. Soon after the Earth Corps begin their journey into the Earth, they run into D. Compose. They drive him back with some flares, but then Tendril attacks them. During the battle, they discover the Granites, who hold Tendril off while the Earth Corps escape, only to run into D. Compose again. However, the Redwoods above them open up the Earth’s surface with their roots, causing a beam of light to blind D. Compose, and helping the Earth Corps to escape. Afterwards, the Earth Corps find out their budget has been cut. Sandra arrives however, and tells them that she will fund their expeditions into the Earth provided that she come along. They accept her offer, and then proceed to design and construct two vehicles, the Terrascout and the Trappeur, to aid them in their expedition. They take them into the Earth, and as they enter the Mojo Discontinuity they are attacked by D.Compose. He escapes, and tries to seal them in a cavern. Auger drills through the wall though, bringing them to the Earth’s Mantle, and suprisingly find it is filled with diamonds. Meanwhile, Blackthorne has followed them into the Earth, wearing an exo-suit he designed based on their plans. The Earth Corps eventually reach their destination where an where the Granites are fighting Tendril and D. Compose who are trying to reach Metlar, trapped above them. The Earth Corps join the battle, but when they shoot Tendril, the two pieces that fall off regenerate into more Tendril monsters. Eventually D. Compose and Tendril manage to get to Metlar, causing Magnokor to release him. Once free, Metlar captures Magnokor and has Tendril take him to his lair. The Earth Corps attack Metlar with the Trappeur and the Terrascout, but he destroys them. They continue to fight, and eventually cause him to fall, giving them a chance to escape. They meet up with the Granites again, and they inform them that another human is attempting an alliance with Metlar. They find that Blackthorne has captured Metlar with his suit’s magnetic field. Sandra distracts him and D. Compose captures her. The Earth Corps then attack D. Compose, while Tendril takes the opportunity to knock Blackthorne down, breaking the magnetic field on Metlar. D. Compose decomposes Sandra into a giant horned corpse and she tries to crush Herc and Auger. They escape and meet back up with the Granites. They discuss a plan to make a stand against the Inhumanoids, and inform Herc Sandra must be exposed to sunlight to return to normal again. They decide to repair their vehicles and split up. Herc takes the Trappeur and some Granites to go to Skelweb, D. Comopose’s lair. Dr. Bright goes to the surface to mobilize the Redwoods to intercept Metlar when he comes to the surface for energy. Auger and Liquidator take the Terrascout to go free Magnokor. Meanwhile, Tendril attacks a civil war monument site, and takes some of the statues. In the Earth’s mantle, Metlar attacks Liquidator and Auger, and causes a lava flow. Liquidator freezes the first wave with liquid oxygen before it reaches them, and they float away safely inside. On the surface, the Redwoods are positioning themselves in front of a military base, and prevent an attempted attack by Tendril. Meanwhile, Herc and the Granites approach Skelweb, and are attacked by a group of knights who had been turned into D. Composes nightmare warriors.
