With news that the powerful synthetic opioid fentanyl is responsible for a continued rise in overdose deaths in New York City and elsewhere, Sam Quinones, independent journalist and the author of Dreamland: The True Tale of America's Opiate Epidemic and (now in paperback), The Least of Us: True Tales of America and Hope in the Time of Fentanyl and Meth (Bloomsbury, 2021), and Courtney McKnight, clinical assistant professor of epidemiology at NYU's School of Global Public Health, talk about the drug and what makes it so life-threatening and resistant to efforts to stem its abuse.