Hundreds died when the Sobral Santos sank on the Amazon, many rumored to have been eaten alive. Jeremy Wade retraces the doomed boat's last voyage and faces adversaries, old and new, as he tries to uncover what was behind the Amazon Apocalypse.

Investigating reports of a brutal riverside mutilation, Jeremy Wade heads to remote wetlands. There, he comes face to face with one of South America's greatest freshwater fighters and uncovers the slasher stalking Argentina's River of Blood.