Thirteen-year-old Iris and her loyal, wheel-bound terrier, Buster, know every inch of their cozy home. But the comfort of their sanctuary is shattered when things begin to disappear into the depths of the family sofa. It's not just loose change and remote controls; it's the sense of peace that usually permeates their living room. When the "Couch Cushion Critter" reveals itself, a mass of domestic detritus and malevolent energy, Iris must dive into the literal and metaphorical dark spaces of her home to save the one companion who has always been her shadow.