In America, it's an epidemic. Now new evidence from Public Health England raises concern about the UK's use of prescription opioids. Dr Michael Mosley investigates this growing problem, meeting patients struggling with addiction and GPs fighting a constant battle to help those suffering from chronic pain. He also uncovers worrying evidence of people abusing over-the-counter opioids and discovers how easy it is to buy strong opioids online. Michael also considers why people are consuming twice the amount of opioids as 20 years ago, and asks the crucial question - do they actually work?