A gutsy twelve-year-old is the only one who can solve the clues, find the treasure, and release an ancient prophecy to save mankind, if she can face her greatest fear. When a new clue is discovered from the Vatican and goes on public display, Indigo's quest turns into a race to the Holy City. With the help of an inquisitive street urchin, Indigo is barely one step ahead of the invisible Sandmen and the Bendy Man, armed with her wits, training and a Swiss Army knife, and 700 years of clues.