Reading The Ludwig Conspiracy, an historical novel by Oliver Pötzsch, opens up dark passageways into the side notes of history. The book itself is a fast-paced thriller with unexpected and persistent villains, both past and present. Published in 2011, eight years after Dan Brown’s The Da Vinci Code, Pötzsch’s book also draws on secret codes and byzantine intrigues and superficially seems to ride Dan Brown’s wave.

You know King Ludwig II of Bavaria as “Mad King Ludwig,” who commissioned the building of Schloss Neuschwanstein, famous as the Disney World castle. He also built Schloss Linderhog and an imitation Versailles known as Herrenschiemsee. Ludwig was born in 1845 and crowned king in 1864. He was a Roman Catholic who struggled with his homosexuality and he was a patron of the composer Richard Wagner.