The film was made based on an excerpt from the novel by Arkady and Boris Strugatsky "The Lame Destiny".
In the novel by the Strugatsky brothers "The Lame Destiny" there is an interesting episode: in a cafe a man sits next to the main character. He introduces himself as a fallen angel and offers to buy ... the score of the trumpets of the Last Judgment. The hero buys the score but does not decide to open it and gives it to someone.