Everywhere they go, people ask for Narcan. But overdoses are increasingly hard to stop.

The coffee table sat on an Eighth Street sidewalk.

The sun had set and there were no working streetlights in that part of downtown San Diego, so during one Thursday last fall you could barely see the four people huddled around its edges.

Heather Newhart walked up and introduced herself. Newhart, a substance abuse counselor who spends much of her time in encampments, spotted a white pill near one of the men. Street drugs aren’t always what they appear to be and she asked if he was willing to test it.