At the reading of their grandmother's will, Dan and Amy Cahill are given the choice of receiving a million dollars or uncovering the 39 clues hidden around the world that will lead to the source of the family's power, but by taking on the clues, they end up in a dangerous race against their own family members.

When Amy and Dan Cahill's quest to find the million dollars takes them to Japan, they must decide whether or not to enter into an alliance with their uncle, Alastair Oh, whose motives for helping them are extremely questionable.

The two kids were last seen in Egypt, hunting for one of the 39 Clues that could make them the most powerful people on earth. But no one has seen the siblings since. Has the ruthless Irina Spasky finally tracked them down? Or worse-- the Madrigals? "A strange telegram lures fourteen-year-old Amy Cahill and her younger brother, Dan, deep into Russia and away from the only trustworthy adult they know. Signed with the initials NRR, the telegram launches...

It's no longer a game. The body count is rising. Shaken by recent events, Amy and Dan flee to a distant land and trace the footsteps of their most formidable ancestor yet: a military leader of mythic proportions. Yet just as the siblings begin to master the art of ancient warfare, they confront a dangerous enemy that can't be felled with a sword: the truth. With the stakes higher than ever, Amy and Dan uncover something so devastating it changes everything...

Amy and Dan Cahill 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.

Fourteen-year-old Amy Cahill and her younger brother Dan thought they could return to their regular lives when they found the 39 clues. But the Vespers, powerful enemies will stop at nothing to get the clues. And with the Vespers rising, the world is in jeopardy.