On a crisp, sunny day in February 2025, a local nicknamed Sleepy, 44, stood across the street from the neat white house in Baltimore where he had been raised by his grandmother. His parents had lived there, too, lost to heroin addiction. As a boy, Sleepy vowed to become a police officer. (He asked not to use his full name to avoid police scrutiny.).

But the streets called, and by his early teens he was selling crack and heroin. In 2007, just a few blocks from his childhood home, he fired a gun into a car carrying gang members whom he feared were hunting him. He went to prison on an attempted murder charge and was released in 2022.

In his absence, the drug world outside transformed — and for drug users, it has become far deadlier. Since the early 2000s, the number of fatal overdoses in Baltimore has soared. And the rate in Baltimore — 110 deaths per 100,000 residents, according to a recent analysis by the San Francisco Chronicle — is the highest among cities with a populations of a half-million or more.

The initial cause was prescription opioids, then heroin, and then, starting a decade ago, a new generation of synthetic opioids, mainly fentanyl. Now, new combinations of ultrapotent lab-made drugs reach the street almost daily, making the narcotics supply — in Baltimore and beyond — more dangerous, polluted and unpredictable than it has ever been. After [PERSON_NAME] came home from prison, his nephew pulled him aside in a park and put a fine point on it.