The city of Baltimore is often called the heroin capital of America.
A whopping 10 per cent of Baltimore residents are estimated to have a drug or alcohol dependency.
Against this backdrop, a small team of drug researchers are trying to do something about it.
They’re studying the behaviour of drug addicts to better understand addiction and the causes of relapse.
And in what is believed to be a world first, they’re using GPS tracking devices to do it.
Colin Cosier reporting.