Annie feels like she's at a good place in her life: happily married, expecting her first child, enjoying a vacation with her extended family at their beautiful coastal home. But then her sister, Sunday, suddenly goes missing. Annie is immediately concerned, but the rest of the family assure her that everything's fine, this is the kind of thing Sunday does, she'll be back... But Annie knows in her heart that something is very wrong, and she won't rest until she sees her sister safe and well. As Annie digs for the truth, she realizes that some of her family are not what they seem. And as she draws closer to uncovering their horrifying secret, she finally understands that she and her unborn child are in terrible danger...