About the book: 1956 / A murder occurred in the library of the Faculty of Chemistry. A librarian girl is poisoned with potassium cyanide stolen from one of the laboratories. It would seem to be a fairly simple case, but the trouble is that the only witness, an outsider who came into the library to make inquiries, cannot say which of the two librarians served him. But this is precisely what determines whether a murder or suicide due to negligence occurred in the library.