In a quiet home in Atlanta, Georgia, Winifred cares for her sister Alicia, bringing dinners of fish up to her room in the attic. But something is terribly wrong with Alicia, something that has left her not quite human.

Flashing back to some years ago in New Orleans, the ever cocksure Alicia has refused to evacuate their family home despite all the warnings about the incoming Hurricane Katrina. Winifred, an incessant worrier, forces them to get supplies from the grocery store despite Alicia's mocking. Unable to leave her sister, Winifred accedes to Alicia's refusal to evacuate and, as expected, the house is flooded by the storm. The two attempt to swim out of the attic and onto the roof but Alicia is swept away by the waters, separating the sisters.

Winifred is rescued a few days later, moaning about her sister deliriously. In her heart, she knows that her sister is dead. Winifred moves to Georgia, where she has family, and is able to get back on her feet. But somehow, a deteriorating creature-which Winifred immediately recognizes as Alicia-staggers down the road to Winifred's new house. Despite her wounds, her new gills, and the smell, Winifred is overjoyed to be reunited with her sister.