A large, black, four-poster bed, possessed by a demon, is passed from owner to owner. In the 15th century, a knight killed the demon, but the demon's blood splashed onto the bed, causing the possession. Those who come into contact with the bed are frequently consumed by it (victims are pulled into what is apparently a large chamber of digestive fluids beneath the sheets).
A running commentary or chorus is supplied by the ghost — if that is the correct word — of an artist (who would appear to be Aubrey Beardsley, though this is never stated directly) trapped behind a painting on the wall.