From PBS and Frontline: FRONTLINE makes a dangerous trip to the battlefields of Syria, gaining exclusive access to rebel forces as they try to unify against extremist Islamic factions that have thwarted the fight against the regime of Bashar al-Assad. With international peace efforts foundering and Western news organizations unable to safely report inside the country, journalist Muhammad Ali crosses into Syria to travel with moderate rebel commanders and fighters as they launch what they are calling "The Second Revolution," this time against jihadis from the Al Qaeda-linked group known as ISIS. From inside the war zone, FRONTLINE gives the most timely view yet of this newest front in the Syrian revolution. Also in this hour: a report from the besieged city of Aleppo, where more than 2,000 children have been killed in the fighting. This intimate portrait exposes what life is like for children who stay behind and are forced to adapt, as the world around them slips further into chaos.