In this fifth installment of the Cahills vs. Vespers, the demands of the kidnappers revolve around an ancient manuscript, writings and inventions of Archimedes, and the Madrigal ring. Amy, Dan, and the rest of their team have no choice; they must do as they are ordered or the hostages will be killed. They rush from New York to Brazil and back while they send Jonah and Hamilton to Italy in search of clues. The boys actually run into a scholar who is an expert on Archimedes and learn some valuable information, but it may be too late. The identity of the Vesper traitor in their group is finally discovered and there is a confrontation with some gunfire involved (but I'm not telling who). Everything seems to be moving faster and faster as the final pieces of ransom are turned over and the Cahills await the release of their loved ones.
I am anxious about what will happen in the next book. Will the Vespers actually keep their word and release the hostages? What are they trying to make with all the relics and information they have forced the Cahills to supply? Will Dan actually give in to the temptation of the formula? Is Amy and Dan's father really still alive? We will all have to wait and find out. In the meantime, you can always visit the website that Scholastic has set up for The 39 Clues and read (or re-read) the series - since we have all the books in the library.