Glass House: The Good Mother 2006 on netflix

One year after losing their son David, Eve Goode and her husband Raymond Goode adopt the orphan Ethan Snow (and his teenager sister Abby Snow and bring them to their mansion nearby a lake. Abby faces difficulties of adaptation in her new home, and she confronts Eve, who proves to be deranged and unstable. When Ethan gets sick, Abby tries to contact their friend, detective Ben Koch, and she realizes that her brother and she are trapped in the house.