Electric Executioner

"Jeremy Wade travels to Brazil's "wild west" in search of a river monster that has killed three cowboys. The search for the culprit sends him deep into prospecting cattle country, where he discovers the shocking truth about a fish he's never caught before. He has to combat all his fears to catch this monster, and after a long chase, Jeremy finally corners his elusive prey in the most unexpected place. All he has to do then is catch it without getting killed."

Synopsis
Jeremy Wade returns to the Amazon to search for a mysterious and deadly killer with a reputation to match its awesome ability. Hearing the stories of three cowboys in Pará dying at the same time without any bite marks on them, he rules out piranhas and stingrays.

After hearing a witness' claim, he concludes that the killer was an electric eel: an 8-foot, snake-like fish that possesses the bizarre ability to produce up to 600 volts of electricity.

Following stories of "invisible powers", he journeys all over Brazil, searching for the elusive fish. Jeremy then comes across a story that confirms the eel's ability to kill a man, but he still tries to find out if it can kill three as the story claims.

After searching through the smallest of ponds he can find in the dry season, he finally finds a large eel in little more than a mud-puddle. After fishing it out, Wade makes a startling discovery that could possibly explain three men dying at once.