underground screaming monster chasing people in caves

Near a remote town, the repeated dumping of toxic waste causes an underground cave dweller to mutate into a hideous monster. A construction team that is digging a tunnel accidentally disturb the creature's habitat causing it to attack.

A group of friends fight for their lives against bloodthirsty creatures lurking in an underground military base.

After years of underground atomic testing, one of the animals living within the Wisawa caves (a system that stretches from Phantom Lake to the Deadlands) has undergone a radical and unimaginably horrible transformation! While exploring the caves, Dr. Vincent Edwards and colleague Rosemary Bennett stumble across evidence in the disappearance of local children. After reporting the find to the local sheriff, Dr. Edwards and Rosemary are tapped to lead a rescue attempt. Along with the sheriff and small-town farmer Stan Johnson (the children's father), the rescue party quickly comes to the realization that if the caves don't get them, whatever unseen terror lurking in the shadows just might!

Bigfoot hunter Bill Brock from Maine searches for monsters in caves

When a group of isolated people in the Greek mountains set off a cave explosion, they are menaced by an invisible shrieking dinosaur that had been buried for eons

A gold thief and his gang use a skier's lodge and meet a monster covered with cobwebs.

Three young adults, obsessed with the horrors of the modern world, find themselves trapped in the depths of a sprawling underground subway, which gradually transforms into a massive, nightmarish organic entity, eager to assimilate them for good.

When a group of cavern tour guides hear an old tale of a sacrificial cult performing rituals in the cave, they sneak down into the restricted areas to find out more. Skeptical about the legend, they end up summoning a demonic presence that refuses to let them leave.