River Monsters: Vampires of the Deep

On the Canada-US border lies a vast lake that hides a dark history. For Native Americans it's an ancient and sacred site, but recently something has risen up from the depths to attack swimmers, and stories abound of an invasion of primordial bloodsuckers. Extreme angler Jeremy Wade plunges into the heart of a waterfall in the Pacific Northwest on a mission to catch the oldest river monster of his career