Flowers In The Attic 1987

There are secrets Chris (Jeb Stuart Adams) and Cathy (Kristy Swanson) never knew about their parents. After their father dies, the teenage siblings, along with their younger brother and sister, are sent to live with their cruel grandmother, Olivia (Louise Fletcher). Olivia is disgusted by the children -- she knows their mother (Victoria Tennant) and father were actually cousins -- and locks the brood in the attic. The kids then try to keep their spirits high in spite of their bleak situation.