Sarah should have left Montgomery County when she had the chance, but now it's too late. She is trapped on the rooftop of her family home which is almost completely submerged by dark flood waters. The air smells of a mixture of sewage and mold and it's still raining. Alone with only her thoughts Sarah is mad she did not leave town years ago when she was right out of high school, before she became the one things she dreaded most; her mother.

Haunted by the occurrence of an eerie thumping sound, Sarah is startled when she discovers a large hairy animal, almost the size of a cow, brushing against the corner of her house. What is it? Where did it come from? What other horrors are hiding in the dark water?