Representatives of one of the foreign intelligence services became interested in Professor Ananyev’s discovery. Even failures do not stop spies and saboteurs striving at all costs to achieve their goals. The cabin boy from the schooner "Columbus" Mark Zaviryukha, the daughter of professor Lyuda, the strange girl Yasya Naidenka and their friends are involved in the cycle of deadly events. A well-known novel, the author of which died during the Great Patriotic War, is published in a new translation. Sign of information products 12 +