PHARMAGEDDON: HOW AMERICA GOT HOOKED ON KILLER PRESCRIPTION DRUGS

The Kentucky number plate on Chad's pick-up truck, parked round the back of a doctor's clinic in Palm Beach, Florida, reveals that he has just driven a thousand miles, 16 hours overnight, to be here - and he's not come for the surfing.

"It's my back," he says, rubbing his lower vertebrae. "I'm a builder. I fell off the roof and hurt my back."

That's odd, as we have just watched him run out of the clinic and over to his truck without so much as a limp. He's clutching a prescription for 180 30mg doses of the painkiller oxycodone.

Chad is one of thousands of "pillbillies" who descend on Florida every year from across the south and east coasts of America. Some come in trucks bearing telltale number plates from Kentucky, Georgia, Tennessee, even far-away Ohio. Others come by the busload on the apocryphally named Oxycodone Express.