"The Truth About Syria" by Barry Rubin. A very readable, not over-long recent socio-political history, and while it is about Syria, it really gives excellent snapshots of the other major players in the region and their agendas. In that sense it's a good introduction and overview of the situation we see today.
It covers from the rise of Baathism and Hafez Assad to the present-day rule of Bashar Assad, and relations with other Arab states, the West, and Israel. It emphasizes the tenuous balance the Assads keep between the diminishing secular Baathist Muslims, a Sunni majority falling under the influence of religious conservatism of the Muslim Brotherhood, as well as very significant Kurdish, Christian, and Druze minorities -- all ruled with increasing isolation by the Alawites, a tiny 'Shia' sect that even mainstream Shias consider pretty heretical.
He makes a very compelling case that the last thing Syria could stand would be peace in the region because the moment there is no chaotic external threat, and thus no possibility of seizing territory to make 'a Greater Syria,' the Alawites will not be able to continue their repressive and corrupt rule in the face of so many suddenly unoccupied internal rivals. The sectarian civil war, he suggests, will make Iraq look like a hootenanny.
When you look at Syria's ongoing two-faced and stop-start behaviors and their support of every type of terrorist organization for 20-plus years in this light, it all fits together really tightly.