A nanny who roams at night in the form of a seal – that's almost everyday life for the three ???. If it weren't for the fact that this nanny has been buried in a cemetery by the coast for years! When Justus, Peter, and Bob start their investigation, they realize that they have fallen into a dangerous web of intrigue, betrayal, and power games. Who can the detectives even trust anymore? The truth seems to lie on the ocean floor, hidden in the depths of an underwater forest.