Having just obliterated one of the gnarliest rum & cokes in recent personal history at an awkward social event, I was already feeling a little emotional. So it’s possible that “The Visitor” had a heightened effect on me. The bar was literally next door to the Landmark Sunshine Cinema in SoHo, so, having bought my ticket, I was able to move from a leaning position against the lounge jukebox to a leaning position against the cinemaplex urinal in a matter of seconds. Then, even before the ice cube in my mouth fully melted, I was seated and ready for the evening’s good long cry.

My eyes water sometimes, admittedly, when I watch movies. What sets me apart, though, from your normal crier, is that I only tear up at happy moments: a reunion (“Antoine Fisher”), a slow-clap (“Cool Runnings”), a carry-off (“Rudy”), etc. Almost never do my eyes water at sad moments. Just keep that in mind.

“The Visitor” opens with a series of “highlights” of Professor Walter Vale’s life, the point of which is, it’s boring. Walter Vale (Richard Jenkins, “Six Feet Under”) is bored. He reuses his syllabus each semester. He’s frigid and uncompromising with his students. He takes piano lessons because he feels like he should.. The message is that he’s resigned. His wife is dead and so is his passion for academia, if there had ever been any. We saw a similar jaded professor character earlier this year in “Smart People,” sharply played by Dennis Quaid, who, reinvigorated by a romance with a former student, finds his way again in his field and as a father. One can only guess that something will free Walter’s boots from the muck as well.

This time, it’s not romance, but an African drum, that’s able to inject a little life into a somnambulant academic. Reluctantly returning to New York for a guest lecture at NYU, Vale goes to stay in his apartment that he hasn’t used in many months, only to find it inhabited by an immigrant couple who have been scammed into thinking it was vacant. After a painful exchange, husband and wife Tarek and Zainab arrange to gather their things and leave peacefully. As they wait with their worldly possessions on a corner, desperately seeking shelter for the night, Walter, his heart seemingly uncorked by Tarek’s undeniable charm, decides to let them stay with him until they can find a place.

Tarek plays the djembe, a west-African drum, in a local band. Vale, intrigued, picks it up one day a gives it a few curious slaps. Tarek, delighted in his interest, begins to give him lessons, and, before long, the cantankerous Walter Vale is playing djembe with Tarek in a drum line in Washington Square. He’s not especially talented, but he’s welcomed, and his friendship with Tarek blossoms (much to the dismay, at first, of his wife).

Things change suddenly when Tarek, having trouble fitting his drum through a subway entrance, hops the turnstile and is immediately confronted by two stern officers of the law. He and Walter plead that he has paid (he had) and was simply jumping it because of the bulk of the drum, but this is to no avail, and we begin to see the ugly face of the post-9-11 consciousness emerge from the film’s otherwise feel-good atmosphere. Tarek is immediately hauled off to a detention center in Queens, where he is held for immigration-law violation.

To see a character like Tarek, so full of life and positivity, in a jumpsuit and trapped behind a pane of glass, with a desperate wife and mother on the outside (both of whom cannot visit, themselves being illegal), is excruciating. Walter visits regularly and hires a lawyer to work on getting Tarek out, and we see Tarek’s desperation mount to a point of anger, and we can’t help but share in it.

The beauty of the unlikely friendship and the ugliness of Tarek’s legal injustice superimpose to create a madly vivid and tightly wound crescendo that will loosen just about anyone’s plumbing. “The Visitor” is full of love and full of pain full of music, engendering hopes as often as it dashes them. The rare harmony of happy and sad: This is why I spent almost the entire movie blinking, not just at the happy parts.