Frontline: The Battle for Syria

As fighting rages in the streets of Syria's largest city, FRONTLINE producer Jamie Doran and correspondent Ghaith Abdul-Ahad journey to the heart of the insurgency, inside the rebel groups that are waging a full-scale assault on the forces of President Bashar al-Assad. Within “liberated zones” near the city of Aleppo, the rebels not only fight the Syrian Army, but struggle against each other in a bitter rivalry between secular and Islamist fighters. "The Battle for Syria" is an unprecedented portrait of Syria's rebel leaders, the toll of the war on civilians, and the outlines of a potential struggle for power in post-Assad Syria. Also this hour: a look inside the House of Assad.

Airs Tuesday, September 18, at 9pm on Channel 5