On the Canadian-U.S. border lies a vast and brooding lake that hides a dark history. For Native Americans, it’s an ancient and sacred site home to underwater spirits. But recently, something has risen from the murky depths to attack swimmers and stories abound of a nightmarish invasion of primordial bloodsuckers. In a journey that will take him to the heart of a thundering waterfall in the Pacific Northwest, extreme angler Jeremy Wade embarks on a punishing mission to battle the most ancient river monster he’s ever encountered, and reveal the true identity of the Vampires of the Deep.