As a journalist covering post-9/11 terrorism, Scott Shane, a National Security reporter for The New York Times, wanted a deeper understanding of the disturbing arc of recent history, and one of the questions he set out to answer was how President Obama came to embrace so aggressively the targeted killing of suspected terrorists. The result of his inquiry is Objective Troy (Tim Duggan, $28), a gripping and illuminating book that opens with a tightly paced scene that could be straight from a thriller, describing Umar Farouk Abdulmutallab—aka the “underwear bomber”—and his failed attempt to bring down a Detroit-bound aircraft per the instructions of his mentor, Sheikh Anwar al-Awlaki. What follows is a fascinating portrait of American-born al-Awlaki (for whom the military’s code name was Troy) and his transformation to an Al-Qaeda leader in the Arabian Peninsula. Shane also highlights some of the biographical parallels between Barack Obama and the man who would become a high priority target of his administration: both men were born in the U.S. to secular Muslim fathers and both spent parts of their childhoods overseas. The personal details lend a human touch to this narrative of the controversial extra-judicial killing of a United States citizen.