An eleven-year-old boy lives an idyllic childhood exploring the remote coastal plains and wetlands of South Carolina alongside his parents and his dog Teach. But when the boy's eerie and estranged grandfather shows up one day with no warning, cracks begin to form as hidden secrets resurface that his parents refuse to explain. The longer his grandfather outstays his welcome and the greater the tension between the adults grows, the more the boy feels something within him changing - physically - into something his grandfather welcomes and his mother fears. Something abyssal. Something monstrous.