The Lost Island by Douglas Preston
Gideon Crew - brilliant scientist, master thief - is living on borrowed time. When his mysterious employer, Eli Glinn, gives him an eyebrow-raising mission, he has no reason to refuse. Gideon's task: steal a page from the priceless Book of Kells, now on display in New York City and protected by unbreakable security. Accomplishing the impossible, Gideon steals the parchment - only to learn that hidden beneath gorgeously illuminated image is a treasure map dating back to the time of the ancient Greeks. As he ponders the strange map, he realizes that the treasure it leads to is no ordinary fortune. It is something far more precious: a discovery that could perhaps even save his life.