Private investigator, Bernard Devlin, discovers that he is the only benefactor in a will left by an unknown uncle. He travels to Missouri to look into his inheritance and discovers some disturbing rumors.

There is a trail of bodies leading to his late uncle's property and the network of underground caves there. The local law enforcement suspects that Bernard's uncle was a serial killer and are determined to get to get into the caves to prove it.

After hearing praise of his uncle from the people who knew him, Bernard isn't convinced he was a killer. However, there is something in the caves...