Love changes you. So do the Outer Gods.

Now: Alone in a cottage, Lavinia writes to the woman she loved.

Fifteen years ago: Middle-aged Lavinia Whateley escapes her hilly Massachusetts town when the townsfolk decide to sacrifice her on Halloween. After almost dying in the woods, she's saved and housed by the stoic and mysterious Asenath Waite, or Azzie. On the coastal outskirts of East Providence, they start to fall in love.

However, things change when Azzie, with her secret past and the strange "scars" on the side of her neck, begins to transform into an eldritch creature of the deep.