A mystery outside of San Francisco brings together small-town sheriff Paul Del Moral, Japanese author Aki Akahori, and a traveler from Reno who soon disappears, leaving behind his suitcase and a trail of questions.

A group of people awaken to find themselves prisoners in a mysterious house with no means of escape. They are each outfitted with electronic devices attached to the base of their skulls. The chemicals that the brain produces when in pain are collected by the devices, and when it collects a predetermined amount, the doors will be opened. In order to escape, they must hurt themselves and each other.