Nine Lives: My Time as the West's Top Spy Inside al-Qaeda

Aimen Dean (not his real name) was an MI6 spy planted within al-Qaeda, where for almost eight years he worked alongside chemical and biological weapons developers. Dean's memoir Nine Lives (2018) was published after his cover was blown; it has interesting details on not just al-Qaeda's tactics and organizational structure, but also on the nature of spycraft and the usefulness of counter-terrorism.