Defenders of the Underwater City

Fritz and Lena are twins. They constantly argue, but are still very close. So, when one evening Fritz's sea turtle started talking to him, he immediately shared this with his sister. Lena, of course, mocked him, saying that it was all a dream. Then things got even stranger. Fritz heard his new classmate talking to a sea urchin and it was answering her! Lena laughed at that too, but then this classmate invited Fritz to a meeting, promising to explain all these oddities. The brother and sister went to the meeting together. And here’s what they learned: there is a hidden city under the water called Almaris, and it needs protection…