The new film “Reign Over Me” opens with a shot of a man zooming through the streets of New York City on a motorized scooter. It is notable for the emptiness of the streets and the grace of the rider. The man is profoundly alone in the midst of a bustling metropolis of millions of people. In exploring how the man came to be so alone and the consequences of letting someone else into his solitary life, “Reign Over Me” becomes an affecting meditation on the nature of grief and love and, more importantly, on the importance of forging and maintaining connections to other human souls.

The premise of “Reign Over Me” is simple. Alan Johnson is a successful dentist in New York City, with a beautiful family and a thriving professional life. He unexpectedly runs into his old college roommate, Charlie Fineman, whose wife and children—his entire family—were killed in the 9/11 terrorist attacks. Alan helps Charlie begin to deal with his grief and learns some valuable lessons along the way.

The actual story, though, is much more nuanced. Although Charlie’s loss and sense of isolation is obviously much more profound, Alan is, in many ways, just as lost as his old friend. Charlie spends his days and nights in an adolescent state of suspended animation—drinking root beer, eating Chinese food, listening to rock music, playing video games, attending movie marathons and continually redecorating his kitchen—all in the effort of driving the terrible events of the past from his mind. While Alan is more functional, in many ways he is just as isolated. He deals with his patients, cares for his aging parents, is bullied by his partners and is controlled by his wife. He is frustrated by his life but does not have the resources even to express his unhappiness. The closest he comes is his habit of waiting for a psychiatrist in his office building to close up her office, then following her out of the building, badgering her for advice for a “friend.”

When the two old roommates meet again, life is changed for both. Although Alan is at first simply intrigued by Charlie’s unique lifestyle, he soon realizes that Charlie’s hermit-like existence, though functional, is hardly healthy. As Alan tries to help Charlie face his demons, both men learn valuable lessons about life, loss and friendship. One of the most profound things that becomes apparent during the course of the film is that a connection to another person, any kind of friendship, is the most important thread that we have tying us to the rest of humanity. The men learn to gain confidence in themselves, and even define themselves, through their growing friendship and their strengthened ties to others.

Highlighting the movie are the performances of the main characters. Adam Sandler, in a departure from his trademark comedic roles, plays Charlie with a nuanced skill. Never maudlin, Sandler shows Charlie’s desperation in bursts of anger and despair. His final confrontation with his late wife’s parents is especially heartbreaking and effective at showing the depths of the character’s grief.

Don Cheadle as Alan carries the weight of the movie, and he shines while doing it. He delicately inhabits the character of Alan and makes him both sympathetic and empathetic in a very believable way. Weary and downtrodden at the beginning of the film, Cheadle slowly brings Alan to life over the course of his friendship with Charlie. At the end of the film, we see that Alan does not have all the answers, but we have confidence in his ability to re-discover the joy in himself and his family.

Sandler and Cheadle are backed up with a fine cast of supporting players, including Jada Pinkett Smith as Alan’s confident wife, Liv Tyler as the sympathetic psychiatrist and Donald Sutherland as a wise judge who holds Charlie’s fate in his hands. The city itself also becomes a supporting player. New York is shown as a brightly lit place for opportunity and fun, but always with a solemn reminder of the tragedy that occurred on its streets and in its skies on Sept. 11, 2001.

Although the premise of the film is very somber, the tone is handled delicately and often with humor by director Mike Binder. The subject matter may be serious, but by the end the message is one of renewed faith in humanity and community.

“Reign Over Me” is, at times, however, overlong and in need of a more judicious editor. In addition, some of the supporting characters need to be more well defined, especially the patient who is over-attached to Alan and becomes involved in Charlie’s plight. Adult themes and language are handled with taste.

The title of the film comes from a song by The Who that is a favorite of Charlie’s. His ever-present earphones offer him a way to drown out his own thoughts, but the songs he chooses are often a reflection of those things he does not want to think about. Songs by The Who, Bruce Springsteen and Jackson Browne create an appropriate and moving soundtrack to a life defined by sadness and loss.

“Reign Over Me” is not a perfect film, but it does offer two touching characters and a memorable friendship that serves as a reminder of how important other people can be.