Arsene Lupin 9: The Return of Arsène Lupin (Aka the Golden Triangle) - Maurice Leblanc

The Golden Triangle (also known as The Return of Arsène Lupin) is set a couple of years after the events of 813. Captain Patrice Belval, learning of a threat to his beloved nurse Little Mother Coralie, rescues her from her would-be assailants and is promptly dragged into a plot involving her husband and millions of francs worth of gold. As layer upon layer of conspiracy emerges with seemingly no obvious thread to follow, there's only one man who can be counted on to uncover the truth—Arsene Lupin. But Lupin is just a memory with a gravestone marker? But are things ever what they seem to be with Lupin?