River Monsters: Alien Sharks

Second of a three-part prehistoric special, as freshwater detective Jeremy Wade embarks on a mission to uncover monsters from centuries ago. He is on the trail of alien-like super sharks, from the very first river monster - an eel-like horror - to a lethal giant nicknamed the buzzsaw killer. He tracks down an extraordinary living fish that links back to long-lost worlds, but which of the prehistoric terrors has the edge?