The Ludwig Conspiracy by Oliver Pötzsch
Fiction
What it's about: A rare books dealer and an art detective are forced to go on the run when they start investigating a diary, written in code, about Ludwig, the fairytale king of Bavaria, who was declared insane, disposed, and found dead the next day.
Reviewers say: "While readers will find broad parallels with Dan Brown's thrillers, Pötzsch's sophisticated plotting and good use of a real-life historical puzzle place this far ahead of most Da Vinci Code wannabes" (Publishers Weekly).
Good to know: This is very enjoyable on audio, read by the excellent Simon Vance, British accent included. Available from hoopla.