Here be proof that the Olsen family gene pool contains both acting talent and the capacity to produce normal-sized humans. Elizabeth Olsen, younger sister of Mary Kate and Ashley, is a revelation as a young woman who escapes a creepy cult headed by a soft-spoken sexual predator (John Hawkes), only to find herself haunted by traumatic visions. She isn't sure whether she's dreaming or reliving terrible memories, but what is certain is that her sister (Sarah Paulson) and brother-in-law (Hugh Dancy), having offered her refuge, can't handle her instability. Olsen nails the multiple layers of her character's fractured psyche, deftly toggling between wide-eyed innocence and feisty intelligence. She animates a memorably broken character sketched out by writer-director Sean Durkin, a fellow feature-film newbie whose precociously steady hand guides this dread-soaked psychological drama.