Day of Doom (The 39 Clues: Cahills vs. Vespers, Book 6)

In the gripping finale to the Cahills vs. Vespers series by bestselling author David Baldacci, siblings Dan and Amy Cahill embark on a perilous global treasure hunt after a shadowy organization kidnaps seven family members. As they collect a series of bizarre ransoms to secure the hostages' release, they uncover Vesper One's chilling plan that threatens millions. Racing against time, Dan, Amy, and their friends must thwart this dangerous scheme to save the world from disaster.