It sounds like something from Carlos Ruiz Zafón’s The Shadow of the Wind and his The Cemetery of Forgotten Books: a huge volume containing thousands of summaries of books from 500 years ago, many of which no longer exist. But the real deal has been found in Copenhagen, where it has lain untouched for more than 350 years.
https://www.theguardian.com/books/2019/apr/10/extraordinary-500-year-old-library-catalogue-reveals-books-lost-to-time-libro-de-los-epitomes