Dark Lights are devices used by the Styx to interrogate and control the minds of their victims. They resemble a desk lamp with a flexible stem, on top of which is a dark purple bulb set in a shallow shade. The Dark Light is connected by a cable to a small box with controls. Upon activation, the device vibrates, and the bulb flares a harsh orange before turning an intense purple. The Dark Light uses subsonic technology to disrupt the victim's brain and implant suggestions by the user, creating an unquestioning slave. It is first seen after Will Burrows and Chester Rawls are imprisoned in the Hold shortly after discovering The Colony, where the Styx use it to interrogate both boys.