When seven members of their family were kidnapped by a sinister organisation known as the Vespers, thirteen-year-old Dan Cahill and his older sister, Amy, vowed they'd stop at nothing to bring the hostages home. But then the ransom comes in and the Vespers demand the impossible-Amy and Dan have just days to track down and steal an ancient map. The only catch? No-one has seen the map for half a century. Now Amy and Dan are on a desperate search that will lead them to the Nazis, spies, a mad king and some of history's dirtiest secrets. It's the race of their lives... and one misstep will mean certain death for the hostages.