Vladimir Korchagin (1924) is a Kazan mineralogist, a famous science fiction writer who has published more than a dozen major science fiction novels and stories (“The Secret of the River of Evil Spirits”, “Astian Edelweiss”, “In the Name of Humanity”, “Prisoners of Fear” ", "The End of the Legend", "The Woman in Black", etc.), winner of the Literary Prize named after. G. Derzhavin. At one time, V. Korchagin was blessed by the patriarch of Soviet science fiction, Ivan Efremov. Today we offer a new story by the writer, which in genre terms can be described as a science fiction detective story.