Storm Warning (39 Clues, #9) (edition 2010)

Throughout the hunt for the 39 Clues, Amy and Dan have encountered some of the darkest aspects of history . . . and had to deal with the role their family played. But are they ready for the truth? In this thrilling ninth installment, Amy and Dan hit the high seas as they follow the trail of some infamous ancestors to track down a long lost treasure. However, the real prize isn't hidden in a chest. It's the discovery of the Madrigals' most dangerous secret and, even more shockingly, the true identity of the mysterious man in black. In this exhilarating installment, Amy and Dan discover long-hidden secrets of the Cahills--a secret so dangerous that people died to protect it. The knowledge leads the siblings to a final showdown with the Man in Black. Will Book Nine be the end of Amy and Dan? Or just the end of everything they think they know?