It was a grotesque scene. A couple of drug addicts so desperate to get their fix that they had injected right outside their dealer’s house – and were then hit instantly by the effects of a deadly new synthetic opioid many times more powerful than heroin that is flooding the streets of America.

The police swung into action. Such scenes are wearily familiar in the country’s overdose capital. ‘C’mon girl,’ said one officer as he syringed Narcan – a drug that counters opioids – into the slumped woman’s nose. ‘Here she comes. Wake up, little Suzy.’

Her eyes opened and she looked at me. ‘What’s going on?’ she whispered. You could almost see her brain start to function.