The Name of the Rose — Umberto Eco (1980)

Umberto Eco's medieval monastery mystery — in which a Sherlock Holmes-like Franciscan friar investigates murders connected to a forbidden Aristotle manuscript — is simultaneously a page-turning detective story, a philosophical meditation on knowledge and dogma, and an extraordinarily erudite exploration of semiotics and medieval theology. Its blend of intellectual rigour with genre storytelling remains unmatched.