Sam Quinones probably knew he was not done telling the story of America's opioid painkiller epidemic. He told the story in his book Dreamland, showing the pain caused across the country by the overdose deaths of people seeking to relieve pain.
Then came Fentanyl, and a new crop of dangers from drugs. It's not all a wasteland; Quinones relates successes in communities keeping addiction at bay in his new book The Least of Us.
He returns to the Exchange to share some of the stories from his more recent travels.