After the movie screening in the Tribeca Cinema in Lower Manhattan as he settled into a stool, microphone in hand for the Q and A, Chris Herren rubbed his left knee — the knee that hurt too much to continue to play for the Boston Celtics and accelerated his dependence on drugs and alcohol.

The occasion was a preview of an ESPN documentary (“Unguarded” — Nov. 1, 2011, ESPN, directed by Jonathan Hock) on the high life of this gifted athlete from Fall River, Mass., who wowed them at Durfee High School and onto a pro career that was as brilliant and transient as a comet in the autumnal sky.

You will want to see this film if only to marvel at the moves this basketball guard displayed from his days in the playgrounds of Fall River, to Boston College, to Fresno State under the wing of the legendary gnome — like Coach Jerry Tarkanian. Drafted by the Denver Nuggets in 1999, he was traded to the Boston Celtics in 2000. Man, could this handsome, beaming, arm-pumping athlete drive, pass and shoot. Even under the influence.

But ultimately, his arms were where he stuck a needle loaded with heroin. He traded a shelf of trophies for a rap sheet of felony convictions. His fans booed him. His family cried from the pain he brought upon himself and them. He converted “nothing but net” into nothing but a life compulsively driven by dope. As painful as that is to watch, imagine what it must have been to live.

Chris Herren went from drinking and grass to his first line of cocaine when he was 18. But it was narcotic pain pills that took him to the major league of drug addiction. First it was Percodan™, then Vicodin™, but not until Ocycontin™ did he become a pro. Life centered no longer on basketball: it centered on scoring this pill that has become a nationwide killer of people, not just pain.

There is an expression in the world of addictions: “The man takes the drug, the drug takes the drug, the drug takes the man.” Soon Herren was taking Oxycontin™ not to get high, but to manage the withdrawal, the “dope sickness,” that comes when the body is denied a substance upon which it has become dependent — the drug takes the drug. When his wife took the car keys so he couldn’t drive to his drug dealer 12 miles away, he got on his 10 speed bicycle and pedaled, on the highway, to get his fix. When he went to play basketball abroad — no longer U.S.A. material — first in Italy, then China, Turkey, even Iran, he upped his game to heroin when pills were not readily available. The drug had taken the man.

He had been at rehab a few times — in college and the pros. I have learned no one ever knows when the life-long process of recovery will “take” — when the repetitive relapses will transform into days, weeks, months and years of sobriety. For addicts, families and my fellow clinicians, the message is never give up. You may not be able to predict when that will happen, but it sure does, more often than we imagine.

As it did happen with Chris Herren. He was blessed with a loving and enduringly supportive family. He had not only the gift of being a great ball player, but he had (has) the gift of being amiable — the kind of person you want to succeed, almost no matter how much he has hurt you and others. He was given really good treatment. It was Daytop, a drug treatment program in the New York area begun in the 1960s and the unbending demands of its counselors, that helped Herren find his heart and soul once again. The man has emerged from the drug.

Chris Herren is the father of three children and still married to his childhood sweetheart. He is now more than three years into his sobriety and coaching youth basketball. His smile warms your heart. You want him to win. He tells his story with humility and with the hope that someone, some youth or aging addict, or person at risk for a life too full of ruin, will find hope, treatment and the road to recovery. One day at a time.