A disturbing report from Southeast Asia, of something in the water that's sliced cleanly through a young man's testicle, is enough to lure freshwater detective Jeremy Wade to the shores of the Mekong - a river long renowned for its monstrous fish.

For years fishermen have been vanishing in Alaska's remote and unforgiving wilderness - their deaths unseen, their bodies never found. For freshwater detective Jeremy Wade, a recent fatal incident sends him on a search for possible suspects.