Living deep in the dark corners, driving the sun-dwellers out of their mines, caves and cellars, the knockers use traps, natural features of the underworld, and their own throttling hands to defend their lairs. They creep, almost invisible in the inky darkness, blending into the stone, tapping and mining, vanishing as soon as light comes near. Instinct: to drive others out

• unseen but heard, the knocker separates its foes and strangles them
• make use of natural dangers to trap and destroy
• where there is one, many lurk in the dark