Thirteen-year-old Dan Cahill and his older sister, Amy, thought they belonged to the world’s most powerful family. They thought the hunt for 39 Clues leading to the source of that power was over. They even thought they’d won. But they were wrong. A powerful new enemy, the Vespers, has emerged from the shadows, plunging Dan and Amy on a dangerous journey that will take them from Rome to the ancient city of Timbuktu. If Dan and Amy don’t stop the Vespers in time… the whole world will pay.