Outer Dark is the story of incestuous siblings Rinthy and Culla. The siblings live together in a dilapidated cabin somewhere in the South in a timeframe roughly around the Turn of the Century. When Rinthy bears Culla's son, Culla takes the child into the woods to die and claims to Rinthy that he did not survive the birth. Rinthy, sensing the lie, sets out to find her child. Culla wanders aimlessly on a Cain-like quest to outdistance his sins.