Police raids at recycling firms across the West Midlands have revealed 11 men being treated as slaves - one of whom was working despite having a broken shoulder.
Three men, aged 52, 47 and 26, have been arrested on suspicion of paying their Polish staff just £1 an hour at CAP Recycling in West Bromwich and Black Country Recycling in Oldbury.
"Police intelligence suggested eastern European men were being exploited at the unit and being paid just £10 for working long hours," says West Midlands Police inspector Colin Mattinson, who led the operation.
"It's believed the men taking advantage of these people – and playing on their vulnerabilities by plying them with alcohol – were living luxury lifestyles and driving around in high-value cars."
Six Polish men were found at the two businesses, three at a flat in Great Bridge – believed to be where some of the workers were living – along with another two in a van outside a suspect's address in West Bromwich's Hope.
One of the men had apparently been working despite having a broken shoulder, while others showed signs of malnutrition and alcohol dependency. They have now all been taken to a reception centre in Tipton, where they are being supported by the Red Cross.
"We've found evidence suggesting some of these men were sleeping at one of the recycling units and bedding down on waste cardboard," says Inspector Mattinson.
"Suspected victims will receive medical attention and support before being spoken to by our officers with the aid of Polish interpreters."
The Home Office estimates that there were 10,000 to 13,000 potential victims of modern slavery in the UK in 2013, the latest year for which it has figures. Last week, Theresa May pledged to improve resources to tackle the problem, a year on from introducing the Modern Slavery Act.
"Convictions are up, more victims are getting support and there are more police investigations into this abhorrent crime," she said.
However, the police say that modern slavery remains largely hidden, and urge people to be on the alert.
Signs to look out for, says Inspector Mattinson, are large numbers of people staying in multi-occupancy houses, being ferried to and fro in vans or minibuses early in the morning and late at night.
"Cruel individuals are making large sums of money on the back of others' misery – so please call us if you suspect people are being exploited in your community," he says.