He unfolded the map of the underground network beneath the city.

The law was intended to break the underground network of people who make and trade child pornography.

An underground industrial network will have to be brought into being.

There's an underground network out there and it's not easy to get into.

More than 200 people were released and disappeared into their underground network.

So the underground network had been crime ridden almost from the beginning.

This must have been added to the underground network fairly recently.

This underground network is the only way to connect those five stations.

There are underground networks that maybe we don't know about.

They come through the underground network of domestic violence shelters.