with major support from jon and jo ann hagler. (chatter on radio) >> ramita navai: i'm traveling through northern iraq, heading to the district of al fat-hah. until recently, this was isis-held territory. we've been driving for a few miles north of the country and every now and again we come across a scene like this. this is the town of beji. i should say it was the town of beji, just look at it. i'm on my way to meet a militia fighting against isis. with the world's attention focused on the battle in mosul, this is one of the war's hidden fronts. few journalists come here. you can see how close we are to isis now. on both sides of the road you can see black smoke billowing out, and that's from oil wells that isis have set on fire. this unit has advanced deep into isis territory. alongside the iraqi army, militias like this have played a critical role in driving back isis across iraq. i want to find out how they operate. how far are they? >> navai: they're pointing over there and they're saying, that's the black flag of isis. and