"I'm the problem." These are the last words heard on the cockpit voice recording of Pacific Southwest Airlines Flight 1771. The words are spoken shortly before the plane crashes into the California hills. Those three words, following sounds of gunfire, quickly transform an NTSB air disaster examination into an FBI murder investigation. Who was the man behind the voice? How did he sneak a gun onto a commercial airliner? And finally, what triggered his cold-blooded crime, one that took the lives of all 43 passengers aboard.