It started with the busted tie-rods of a Humvee. It continued with the ill-advised order to split an Army Ranger platoon as the Afghan night was coming on. And it finished, on April 22, 2004, with the death by friendly fire of an exemplary young American. But there it did not really end, because of who this fine man happened to be — Pat Tillman, promising NFL star — and because a virtuosic author decided to write a political firecracker of a book about the “cynical cover-up sanctioned at the highest levels of government” that ensued after his death.