Jeremy Wade returns with a brand-new series of the show in which he investigates cases of huge and deadly creatures lurking in the world's waterways. This episode sees him head to the Mekong river in south east Asia, where gruesome tales of a creature capable of slicing cleanly through a young man's testicles lead Jeremy to uncover multiple victims who have been mauled by the same mysterious assailant - can he find and catch this baby-faced killer that appears to be proliferating in the waters in and around Cambodia?