In Louisiana, near the border of Texas, the mother of the young man Paris has a seizure and falls off a bridge while driving her car with her son. He saves himself but is not able to rescue his mother that disappears in Caddo Lake. In a house near the lake, the rebel teenager Ellie lives with her mother Celeste, her stepfather Daniel and her eight-year-old stepsister Anna. Ellie has arguments with her mother because of her father that she never knew and questions whether he really died. When Anna disappears in Caddo Lake, Sheriff Mark Taylor organizes a search party to look for her in the lake. Meanwhile Paris is researching why his mother had seizures when the water level is low in the lake. Ellie decides to look for Anna in the lake and finds a mystery in the lake.