“Help,” a tiny voice cried out into the darkness. Little Betsy trembled, praying someone would hear her, save her. “Please,” she whimpered. “I’m scared.” On the hottest day of the year, as a heatwave takes hold of the Appalachian Mountains, a five-year-old girl goes missing. Just as the sun is setting, a family vacation becomes a worst nightmare—Betsy, with her green eyes, ponytail and rainbow t-shirt—disappears in the woods by Widow Lake. Detective Ellie Reeves is straight on the scene, promising Betsy’s heartbroken parents that she will stop at nothing to find their precious daughter. Hours later, Ellie is called back to the lake. One of her team have discovered some remains near where Betsy disappeared. The bones belong to a local girl, Amy Dean, who vanished ten years ago to the day, along with her two-year-old baby girl Paisley. But why was Paisley never reported missing? And could she still be alive? Ellie is suddenly up against the toughest case of her career. Her instincts tell her that the two cases are somehow connected, and she works day and night to uncover the link. When she comes across some little graves beside the water’s edge, she knows she needs to stop the evil lurking around this tranquil lake. When Ellie discovers a notebook scrawled with the handwriting of a little girl, it could be the breakthrough she needs. Can she unravel a decades-old mystery, and stop the monster claiming innocent lives?