The First Secret of Edwin Hoff

The First Secret of Edwin Hoff is a Batman-meets-Bourne thriller about an elite commando living the unexpectedly public life of a billionaire tech entrepreneur. But when Edwin is called to stop a bio-attack planned to release from a 9/11 plane, he does what a Seal Team 6 fighter would do for his next act, and more. Under deep cover, he protects the world from terror while turning the folks he meets into heroes.

Edwin Hoff is a fiction inspired by a real person: Danny Lewin was a Counter Terror Captain in Israel's equivalent of Seal Team 6. He trained to rescue hostages and kill terrorists with his bare hands. Later he went to MIT for his masters in math and founded Akamai Technologies, becoming a billionaire overnight. The author worked for him there for two years until, on September 11, Danny went to visit customers in California. He boarded AA Flight 11. Amid the horrifying tragedy, Danny left behind this puzzle:

On September 10, he packed up his office. No one knows why.