There are hundreds of adults and children living in tunnels beneath Romania's capital Bucharest.
They've been abandoned to a life of drug addiction.
When the country's Communist leader Nicolae Ceaușescu fell in 1989, thousands of children were left in orphanages.
The barbaric conditions in these orphanages were revealed by the media a year later.
Some of these children moved into the tunnels of Bucharest, and had children of their own.
Channel 4 reporters ventured underground to meet those who live there.
They say the hot chambers reek of a paint called Aurolac, which the addicts snort.
Nicu, left, is actually 17 years old, but his growth has been stunted by drug abuse.
This man is doling out the paint for the equivalent of 50p a hit.
People down in the tunnels are also taking a drug similar to methadone.
The reporters say: "Everyone here is HIV positive, a quarter have TB."
This man is called "Bruce Lee", a name he picked up in his street-fighting days. You can see the scarring on his arms, a result of self-harm.
The reporters say: "There is a twisted order to Bruce Lee's underground fiefdom. Social workers told us he tries to protect the young ones from sexual predators."
He pays protection money to a local gang.
Lee tells the reporters that the people down here are not the scum of society.
He wants them to know that they are a family.
As for Nicu, Bruce Lee won't let him inject any more, but he's still using Aurolac.
Nicu needs anti-viral treatment as he contracted AIDS last year, but the state hospital can't treat him whilst he is still sniffing paint.
Nicu says Bruce Lee was the only one who visited him every day while he was in hospital.
Watch 'Bruce Lee, King of Bucharest's Sewers' in a special report for Channel 4 News tonight (Tuesday) at 7pm.