After a wonderful summer vacation in Mari's homeland, the underwater city of Almaris, Fritz, Mari, and Lena have a cool surprise at the start of the school year: a school trip to a small island in the middle of the sea. During an excursion, they stumble upon an old legend. Somewhere on the island, a pirate treasure is said to be hidden, which includes Poseidon's amulet. However, they are not the only ones wanting to uncover the secret of the treasure, and soon they find themselves in grave danger. But who is their dangerous adversary? And what happens when the magical amulet falls into the wrong hands? A thrilling chase for the truth begins... Jens Wawrczeck narrates the second part of the series with plenty of humor, excitement, and a fantastic variety of voices.