The Earth Corps have successfully defeated the Inhumanoids, and Blackthorne Shore is locked up in the Glades, a maximum security prison. However, the sample of Tendril that was taken in The Evil That Lies Within, regenerates into another Tendril monster, and begins another rampage. The Earth Corps team receives this information and go to stop him, but Senator Masterson will not allow the creature to be destroyed, in hopes of putting it into a zoo. Tendril is then taken to a research facility at the zoo in an attempt to communicate with it through an advanced language computer called Cypheroid. The attempts are believed to be a failure, due to Tendril’s primitive nature. Actually, unknown to the researchers, the attempts were successful but not for the expected intent. Cypheroid plans to help Tendril escape in exchange for Tendril’s cooperation to help the computer retaliate against humans. Cypheroid has Tendril steal different components for it’s plan, which just so happens to include one of the Earth Corps vehicles. When Liquidator and Auger arrive with the Terrascout to try to stop Tendril’s rampage, Tendril takes the Terrascout. Afterwards, Cypheroid, using the Terrascout for mobility, goes to granite city and forces Granaque to have Magnokor release Metlar into the computer’s custady. Afterwards, Metlar and Cypheroid discuss an allience, but only if the computer leads Metlar to the humans. Meanwhile, the Earth Corps take the Trappeur to follow the Terrascouts homing signal (which is what Cypheroid was expecting), and are attacked by Tendril. During this time, Blackthorne and his prisonmate, Dr. Herman Mangler, are contaced by Cypheroid who devises a plan of escape in exchange for their help. Cypheroid has Tendril attack the prison allowing for their escape. However during their journey to freedom, Dr. Mangler falls into a pond that contains a rather large amount of toxic waste. Meanwhile, Cypheroid and Metlar find the Earth Corps scientists, but Metlar then turns on his agreement with the computer. Just as Metlar does this, Blackthorne arrives and fullfills his part of the bargain with Cypheroid, by trapping Metlar. However, Shore had arrived too soon and the Earth Corps team was still alive. Liquidator destroys Cypheroid by dissolving it(and the Terrascout) with some acid. At that moment, Tendril breaks through the ground and grabs Shore, thus freeing Metlar from his magnetic hold. Seeing their present dilema, the Earth Corps escape leaving Blackthorne behind to deal with Metlar and Tendril.
