Frozen from the outside... Frozen with fear inside!

A state-of-the-art prison has been constructed in Antarctica to hold the most dangerous people for the term of their natural lives. With escape, comes death from exposure to the minus 65-degree environment. While drilling into the glacier the inmates hit a pocket of pure nitrogen gas. This gas preserves everything in perfect condition for millions of years. The remains of several guards are later found ripped apart...

Something prehistoric has awakened from the ancient cavern!