Jeremy Wade returns to Australia's croc-infested Fitzroy River for one of his toughest quests yet — to catch one of the world's rarest fish. This shark is so elusive it was only discovered ten years ago, and so rare only a handful of people have ever seen it. Almost nothing is known about this endangered beast. Could it be a man-eater? The expedition turns Wade's knowledge of freshwater killers upside down as these animals seem to break all the rules.