This is the last part of the Inhumanoids: The Movie:
When the Inhumanoids get information out of Blackthrone, they raid a Soviet air base and steal several nuclear missiles.
The Earth Corp finds out that they might be used to destroy the Earth's mantle. They think that Blackthrone tries to help them, but they soon have to admit, that might have been set up and the nuclear explosives should be used on the Earth's core, so the planet would be destroyed.
Afraid of this plan even D'Compose sees that Meltar has gone insane and so he helps the Earth Corp to get to the missiles. They can disable enough of them, so the core wouldn't be destroyed anymore.
In the fallowing battle D'Compose can be sealed again and Tendril is impersonated by the Granites. Magnokor is able to stop Meltar and the Earth Corp is able to arrest Blackthorne.
Now Senator Masterson has to give the Earth Corp a lot of new findings. So they get a new headquarter.
The problem when they move: A piece of Tendril is gone missing...