The Looming Tower is largely focused on the people who conspired to commit the September 11 attacks, their motives and personalities, and how they interacted. The book starts with Sayyid Qutb, an Egyptian religious scholar who visited the United States in the late 1940s and returned to his home to become an anti-West Islamist and eventually a martyr for his beliefs. There is also a portrait of Ayman al-Zawahiri, from his childhood in Egypt to his participation in and later leadership of Egyptian Islamic Jihad to his merging of his organization with Al Qaeda. Osama bin Laden is the person described the most, from his childhood in Saudi Arabia in a rich family, his participation in the jihad against the Soviet Union in Afghanistan, his role as a financier of terrorist groups, his stay in Sudan, his return to Afghanistan, and his interactions with the Taliban. The 1998 United States embassy bombings in Dar es Salaam, Tanzania and Nairobi, Kenya are described, as is the bombing of the USS Cole in 2000. Lawrence Wright also describes in detail some of the Americans involved, in particular Richard A. Clarke, chief counter-terrorism adviser on the U.S. National Security Council, and John P. O'Neill, an Assistant Deputy Director of Investigation for the FBI who served as America's top bin Laden hunter until his retirement from the FBI in August 2001, after which he worked as head of security at the World Trade Center, where he died in the 9/11 attacks. The book also describes some of the problems associated with the lack of cooperation between the FBI, the CIA, and other U.S. government organizations that prevented them from uncovering the 9/11 plot in time. Because The Looming Tower is to a large extent focused on telling the story of the people involved, it does not describe the 9/11 plot and its execution in much detail. It focuses more on the background and the conditions that produced the people who planned and staged the attack, and information about those who were combating terror against the United States.
The words "looming towers" or "lofty towers" appear in the Quran . According to Wright, Osama bin Laden, at a wedding before the 9/11 attacks, quoted the line, repeating it three times: "Wherever you are, death will find you, even if you are in lofty towers".
