Maurice LeBlanc 
The Secret Tomb [EPUB ebook] 

Dorothy, rope-dancer and palmist, arrives at the Château de Roborey with her circus, she’s already observed strange excavations at the grounds. Fate drags her and her motley crew of war orphans into a quest for long-lost ancestral treasure, but a new-found nemesis is close on her trail.

Maurice Leblanc, most famous for his Arsène Lupin stories, here switches to a new protagonist, but fans of his other work will find her strangely recognisable. Indeed, the mystery presented here is later referenced in The Countess of Cagliostro as a puzzle that Lupin did not have time to solve.