News of a foiled Al Qaeda plot has refocused attention on the shadowy, controversial war against terror. According to reports, Al Qaeda's Yemeni affiliates planned to use a hard-to-detect "underwear bomb" to explode a US-bound commercial airliner. The plan failed when US intelligence agents seized the device. So what is the story of the CIA and Al Qaeda? Does Al Qaeda still pose a threat? As ever, a selection of the best reading can help us.
For an insightful introduction, go to Steve Coll's Pulitzer Prize-winning Ghost Wars: The Secret History of the CIA, Afghanistan and Bin Laden. Coll's examination traces the origins of Al Qaeda to early US funding of the Taliban, and argues that western intelligence consistently failed to recognise the threat presented by Bin Laden's new brand of Islamic jihad.
That threat manifested itself tragically on 9/11. Read The 9/11 Commission Report - the official account produced after the attack - for an account so compelling that John Updike called it a "masterpiece by committee".
Meanwhile, Jason Burke's well-regarded Al-Qaeda: The True Story of Radical Islam portrays the organisation at its operational height.
But in its protracted struggle against Al Qaeda, critics argue, the West has lost touch with its conscience. The New Yorker journalist Jane Mayer's The Dark Side says that "rendition" and torture of suspected terrorists became commonplace under the Bush administration. Almost half of those tortured, she says, were eventually released without charge.
Today, without Bin Laden, US officials say Al Qaeda is much weakened; the Yemeni plot serves as a reminder, though, that it cannot be discounted. CNN's Peter Bergen - who interviewed Bin Laden in 1997 - mused on the future of the organisation last year in his acclaimed The Longest War and has just published Manhunt, a thrilling account of the raid that killed Bin Laden.