I Know You're in There (2016)

Plot

Tom Redding's world shatters when his mother takes her own life, unveiling the existence of a mute sister he never knew. Determined to understand their family's dark history, he brings her to their late mother’s secluded house to document her condition. As they delve deeper into the past, they find themselves haunted by a malevolent force that pushes Tom toward insanity. With the weight of their family's secrets bearing down, he must confront not just the supernatural, but the trauma that binds them both.