. >> navai: the unit reaches the town of tal abtah. isis have built tunnels under the streets here. the militia are still clearing them. suddenly, we're told to stop filming. >> navai: why do we have to put the camera down? >> navai: this neighborhood is controlled by the hezbollah brigades, the militia accused of the razaza and saqlawiya disappearances. the men we're with are nervous. what happens when you go in their territory? >> navai: eventually, commander kadoom and his badr fighters reach their destination. (gun firing in distance) >> navai: what was that shooting? >> here, it's good, but maybe go to there, it's not safe. >> navai: kadoom and his men are securing tal abtah's hospital. they've been given the names of sunnis who might be isis collaborators. >> this picture for cutting the hand off someone. >> navai: they're now taking me to an isis tunnel, and isis have built all this network of tunnels in this area. and this is how they operated, and this is how they fought these guys. they'd pop out of these tunnels. god, it's big-- it's a sophisticated tunnel. towards the en