What are the major characters and events in The Looming Tower?

In Wright's work, there is not really one event analyzed. 
It is more of a study of figures and personalities who played major roles in the
coordination and execution of the terrorist attacks of September 11, 2001.  It does not
seek to recreate what happened on that fateful morning, but rather analyzes the people
and figures who played vital roles in the way that day came about.  Individuals like
Ayman al- Zawahiri, whose organization was committed to Islamic Jihad ended up merging
with al- Qaeda.  Naturally, the bulk of the study is dedicated to Osama Bin Laden.  His
background and rearing, as well as his commitment to anti- West principles all occupy an
important role in the book.  At the same time, the book explores how he grew into the
force that was able to finance and coordinate such an elaborate attack like September
11.  Finally, the book spends a bit of time discussing how American attempts were quite
feeble in a general sense, but also focuses on specific people such as Richard Clarke
and John P. O'Neill who fully understood Bin Laden's threat, but whose words were not
fully heeded until it was too late.