DELRAY BEACH, Fla. — It was the kind of afternoon that cold-weary tourists revel in as they sip mojitos near the beach — a dazzling sun, a sky so blue it verged on Photoshopped and weather fit for flip-flops. But the young visitor from Arkansas, curled up into a ball near the sidewalk, had a better reason to be grateful. He was alive.

“You are overdosing on heroin,” Sean Gibson, a paramedic captain with the Delray Beach Fire-Rescue, had told him earlier this year, after the man fell off his bike, hit a chain-link fence and collapsed, blood trickling down his face. Mr. Gibson sprayed Narcan, an opiate blocker, up the man’s nose as he lay on his back and, before long, the man — who had shot up heroin at a recovery group home — sat up, polite and embarrassed. “Thanks, guys,” he said, before being taken to the hospital as a precaution.

In a nation awash in opioids, there are few, if any, places where this kind of scene plays out more often than this artsy beach town of 15 square miles. Here, heroin overdoses long ago elbowed out car crashes and routine health issues as the most common medical emergencies. Last year, Delray paramedics responded to 748 overdose calls; 65 ended in fatalities. In all, Palm Beach County dealt with 5,000 overdose calls.

Unlike other places in the United States that have been clobbered by the opioid crisis, most of the young people who overdose in Delray Beach are not from here. They are visitors, mostly from the Northeast and Midwest, and they come for opioid addiction treatment and recovery help to a town that has long been hailed as a lifeline for substance abusers. But what many of these addicts find here today is a crippled and dangerous system, fueled in the past three years by insurance fraud, abuse, minimal oversight and lax laws. The result in Palm Beach County has been the rapid proliferation of troubled treatment centers, labs and group homes where unknowing addicts, exploited for insurance money, fall deeper into addiction.

“We have these people sending us their children to get healthy,” said Dave Aronberg, the state attorney for Palm Beach County, who established a sober homes task force to combat the problem, “and they are leaving in ambulances and body bags.”