Within The Black

I was watching a movie about ancient creatures that are hostile who managed to escape from the deepest part of the earth and started an apocalypse. I wonder what if that actually happens. How prepared are we, or is that even be possible?

Have you ever heard of the Hallow Earth theory. It's the belief that Earth is actually hallow inside and another civilization and creatures live there. So, you never know. If true, maybe one day all of them might decide to come to the surface