“Reign Over Me” is one of the first films to be able to examine the aftereffects of Sept. 11 without depicting the actual events or responding patriotically. Written and directed by Mike Binder, despite any associations attached to the usual frivolity of Adam Sandler, the film is nothing less than a portrait of the breadth and depth of despair.

As such, it is painful and moving. The film’s humor is either absurdly escapist or it is the type experienced by someone who has reached absolute bottom and can only laugh at how far down he has gone. The power of this film may surprise even Sandler’s fans, but remember, his co-star Don Cheadle rarely makes disastrous career choices.

Charlie Fineman’s (Sandler) life of isolation and distraction began when he lost his wife and three daughters when their plane hit the Towers. Blocking out the sounds of the real world with oversized headphones, Charlie drifts through New York City on a motorized scooter — avoiding the necessary interaction of walking and the confining regulation of driving.

His dental school roommate, Alan Johnson (Cheadle), is a cosmetic dentist with a successful practice. He also has a wife (Jada Pinkett Smith) and two daughters. However, he feels trapped by his frail parents, suffocating relationship with his wife and the disrespectful attitude of his colleagues.

Charlie and Alan haven’t spoken in years, but a chance meeting on the street leads to a tentative reunion. Charlie is shattered, borderline — Rainman in conversation, an unkempt and unfocused wanderer. His apartment is practically bare save a vinyl collection, a gaming console, a giant flat-screen television and a kitchen he’s constantly remodeling.

Alan is troubled by his friend’s state, but finds liberation in Charlie’s unfettered lifestyle. Alan represents a new beginning because he knows nothing about Charlie’s lost family and ostensibly won’t ask questions or challenge the delicate status quo.

Sandler’s performance is vulnerable and exposed. He brings something of the overgrown adolescence of his earlier work but also portrays the fragility of someone who is utterly without purpose or direction. Cheadle’s Alan is neurotic and necessarily imperfect, but still a good man. His patience and sense of responsibility for Charlie is touching.

“Reign Over Me” draws its title from The Who’s “Love, Reign O’er Me” and examines several important questions: What’s the difference between treatment and mistreatment? How important is it to coerce a grieving person to process his emotions? When is an intervention merited versus a selfish imposition of irrelevant external standards?

The fixation on “Love, Reign O’er Me” is a reflection of Charlie’s need for guidance and an explanation for his current patterns. Charlie’s main occupation, a video game called “Shadow of the Colossus,” can symbolize the monsters of Sept. 11, his battle with personal demons and his own reduced existence as a shade of his former self.

The screenplay might have benefited from a more exacting editor (one who would reduce actor/writer/director Binder’s self-cast role, dial down Alan’s personal drama or perceive the lack of wisdom in fixing a traumatized, broken-hearted man up with a litigious woman). However, the story is so effective that Binder’s self-indulgence is forgivable.

The film is long but doesn’t feel overextended. It is also a new contribution to the category of great New York City films, thanks largely to the work of cinematographer Russ T. Alsobrook. Charlie and Alan’s voyages around town provide glimpses and snapshots of fast-paced city life — even if their improbably huge apartments inspire realty envy.

Those around Charlie realize his grieving has to occur on his timetable, not theirs. It’s a triumph for Sandler, with strong performances from Cheadle and the seasoned cast. Though not Binder’s first foray into writing and directing, “Reign Over Me” is his best thus far — a probing depiction of personal loss and growth that succeeds beyond its promise.

“Reign Over Me” was written and directed by Mike Binder.

“Reign Over Me” received three out of four stars.