PARENTS of drug-addicted kids learn the hard way that when we think things can’t get worse, they do. As a teenager, my son, Nic, was addicted to methamphetamine, heroin and other drugs. At 20, he had used most of the illicit drugs known to man. But one night, partying with a couple of friends in his basement apartment in Brooklyn, the combination and volume caused him to overdose. One of his friends called 911.

Nic was rushed to the emergency room, where he was resuscitated. When I spoke to a doctor there, I was told that if another 15 minutes had passed before Nic got to the E.R., he wouldn’t have survived. My son has now been sober for five years. I don’t know who called the paramedics, but not a day goes by when I don’t thank him.

Other parents haven’t been so lucky.

So many of the stories I’ve heard, from parents who have read my accounts of Nic’s addiction, begin the same way. He was a wonderful child, a good student. She was popular, a hard worker.

David C. Humes described his son Greg as “Wonderful and bright. A.P. courses, good athlete. Warm. Loving.” On May 19, 2012, “Greg’s earthly story ends,” David told me. His son overdosed and passed out. Someone — David doesn’t know who — dragged Greg outside and placed him in the back seat of his own car. The person then drove Greg to the hospital and left him in the parking lot, where he was found dead.