OUTSIDE MOSUL, Iraq - Foreign journalists are not allowed to go into Mosul. But CBS News talked to an Iraqi who has seen what's going on inside the city with the militants in charge.
This doctor, who works in Mosul, made his way through checkpoints to meet us a few miles outside the city.
Like the militants, most of its residents are Sunni Muslims who resent the Iraqi government, which is dominated by Shiite Muslims.
The doctor wouldn't show his face - not because he's frightened of ISIS, but because he fears retribution from Iraq's government.
Has ISIS enforced Islamic law in Mosul?
"Actually, they have this idea," the doctor said. "But they are not forcing people."
He told us his hospital only has water for two hours a day because the Iraqi government switched off the water supply.
Are things better under ISIS?
"As the people say, it is better than government," the doctor said. "Because they gave them freedom."
In Internet videos, ISIS shows a very different face - including summary executions of its enemies.
"If you do not think the way they do, you die. That's it," said retired Col. Harry Schute.
Schute fought in Iraq during the U.S. invasion and now advises Iraqi politicians.
He blames Iraq's U.S.-backed government for dividing the country along religious lines - and driving the country's Sunni Muslims into the arms of ISIS.
Can Iraq survive as a state?
"Looking at it right now, I don't think so," Schute said. "I think the Iraq that we had in our vision from a couple of years ago, or whatever, is finished."
Some people have told us Iraq's religious fault lines are so deep that the only way to avoid a civil war is to let the country split apart.