Rumors are spreading through the streets that the legendary diver, the Black Master himself, is announcing a set of students. At the appointed hour, thousands of volunteers gather in one place. But how many of them will get to the test and be able to survive by passing it? And what does it have to do with the stones for which people are ready to risk their lives and go for any meanness? The twelfth book of the cycle. Heroes return with victory after annual adventures in foreign worlds...