It's a battle for survival when a massive piraiba pulls the team down a raging river before they can sample it. Potential disaster greets them at every turn, and the guys are forced to change strategies. Merciless rapids, hidden stingrays, motor failures, lightning strikes, black piranhas and massive falling trees are just some of the dangers the crew must overcome in their quest to sample a giant piraiba for their research. And with a mysterious fish on his line, Cyril gets much more than he bargained for, in a truly dangerous battle.