From Below

More than 300 years in the future a nuclear war occurs, resulting in much more damage than any could have imagined; the massive explosions awaken monsters that had been residing undetected beneath the Earth's surface. Radiation, evolution, or contact with the creatures has supposedly mutated a small percentage of the human race over time, and Sebastian is one of them. Incredible coincidence has Sebastian and several other mutants meet up in an ancient cavern in the mountains, one that might hold the key to saving their world. Danger is always one step behind them, but then again, it might just be a few steps ahead.