Sex trafficking is growing at such a rate it has become one of the largest international crime problems.
By Sarah Portlock
BBC News, Birmingham
Roze and a friend were taken to a hotel in Coventry
When an 18-year-old Lithuanian woman, sold for £4,000 by traffickers, ended up at a house in Warwickshire, officers from one of England's smallest police forces had to deal with the consequences.
The force, which is the second smallest behind the City of London, had to track down the offenders, rescue the girl, and successfully prosecute the gang.
But the operation was so successful, its detectives are now being called on to give presentations to others across the country.
Det Ch Insp Adrian McGee, who led the investigation, said it was the first time the force had been involved in such a case.
"We had to learn on our feet and now other forces are learning from us," he said.
The force's involvement began in August 2005 when the then National Criminal Intelligence Service (NCIS), now the Serious Organised Crime Agency, and Europol, the European Police Office, got in touch.
"We got a phone call saying a girl was at an address somewhere in Warwickshire.
"She was in touch with her mother in Lithuania who had contacted Lithuanian police, who contacted Europol, who contacted NCIS, who contacted us," Mr McGee said.
Despite not having dealt with such a case before, detectives knew what to do.
"Its what we call a crime in action, similar to a kidnapping, which we are trained to deal with," he said.
During her 10 days in the country the girl, known as Roze, had managed to get hold of a mobile phone and contacted an ex-boyfriend who alerted her mother.
"Through a relay of phone calls with her mother we established that where she was staying she could hear trains going by. She described what she could see from the front of the house and knew the name of a pub nearby," he said.
From that information, detectives were able to track her down to a house in Gadsby Street, Nuneaton.
'Gained her trust'
But getting her out was not so easy.
"She always had someone with her. The traffickers had tried to appease her by letting her contact her home and, because they were Albanian, I don't think they understood her conversation. They even took her to have a hair cut. But they had a lot of control over her."
Eventually, the people with her, suspecting the game was up, left her alone in the house.
Officers then had to gain her trust so she could come out of the house and go with them.
Gadsby Street, Nuneaton. Pic by David Rose / Panos Pictures
"You have to remember she was very vulnerable. She did not know anybody and it may be that she could be afraid of police. But we gained her trust and the courage she showed was fantastic."
Police went on to arrest several of the gang members and Roze had the courage to give evidence against them with the result that, in December 2006, they received sentences of between three and 14 years for a range of offences.
The growing trafficking trade - at a time the UK is marking 200 years since the Parliamentary Act to abolish the slave trade - could mean a large drain on police force's resources across the country, Mr McGee said.
"The implications for us were that, while it was being carried out, there could have been other matters that weren't being done. 2005 was a year of big investigations for us.
"But this particular one did not take a great deal of resources.
"There was no manhunt, for example, which requires a lot of officers. But it was an expensive investigation."
It is estimated it will cost the force up to £50,000 in additional costs.
"It was the first and only time this has happened in Warwickshire. We dealt with it robustly and we will do so again if required.
"We were dealing with the exploitation of vulnerable girls' dreams.
"They thought they were coming for a new life and would be able to send money home to their families. Instead they were completely violated.
"It is abhorrent."