The Obsidian Chamber — Christopher Cartwright

In A.D. 79, Mount Vesuvius erupted and a small girl raced for her life along the cobblestone streets of Pompeii. She needed to survive. She needed to tell someone what she had done so that it could never happen again…In present day, while Sam Reilly is on a mission to locate the long-lost shipwreck of legendary explorer Ernest Shackleton, a strange code begins to circulate on the internet. It purports to have the answers to some of the world's most complex engineering and algorithmic problems.The US government's brightest minds are racing to be the first to break what has the potential to be the most powerful code on Earth. And the most dangerous.