In the third Planet Agents book readers are invited to join Planet Agents Jason, Anita, Ben and Marie-Louise on a mission to save the sea before the next full moon! In 48 hours the children have to find and face the four monsters that evil Ivan Von Powervamp has unleashed to destroy the Earth's oceans. In a race against time, full of surprises, water-vampires, scuba diving, and marine kingdoms, young Enviropol Agents will travel the world learning what the real threat to the sea is.