In almost every respect, Tom McCarthy’s new film, the assured, affable, and increasingly angry urban tale “The Visitor,” is steeped in the New York way of life. Its drama is spawned by an act of trespassing — an illegal sublet — that leads an upper-class member of the white majority to forge an unexpected friendship with an illegal immigrant. “The Visitor,” which opens next Friday, ponders how a conservative professor from the suburbs and a passionate musician from Africa would connect when tossed together into a cramped space, and, more thematically, how the intimacy of our urban existence evokes a sense of curiosity and empathy that sets New Yorkers apart.

“Literally, by leaving the door open, we see the ways in which this character has to open his mind to a new situation,” Mr. McCarthy said. “What many have connected with is this notion of just how easy it is in New York to stumble into just about any situation; that cross-cultural element that can bring new ideas, and also new concerns, into your life.”

In 2003, the 34-year-old writer-director, who had already found moderate success as a character actor, exploded onto the independent film scene with “The Station Agent,” an off-kilter character study of a dwarf who, despite his attempts to isolate himself at a rural New Jersey train station, is befriended by an artist and a hot dog vendor. The unique film nabbed prizes at the 2003 Sundance Film Festival for best dramatic feature, screenwriting, and acting (for costar Patricia Clarkson). Mr. McCarthy was singled out as a filmmaker with a flair for visuals, words, and an ability to inspire exciting performances from his actors.

In “The Visitor,” he brings all those talents to the table. Walter (Richard Jenkins, the veteran character actor whose face is more familiar than his name) is a professor lacking a sense of purpose, going through the motions while shuffling between his Connecticut home and office.

Still mourning the death of his wife, Walter is forced to give a prominent presentation for his department at NYU. When he travels down to his little-used Manhattan apartment, he’s shocked to find a strange couple living in his space. They are undocumented citizens who have supposedly leased the loft and made it their home. Walter becomes irate and kicks them out. But when he realizes they have nowhere to go, he invites them back to stay until they can find another place.

“It’s a very, very tricky issue, the issue of illegal immigration,” Mr. McCarthy said. “This certainly isn’t a movie that sets out to be just about immigration. It’s first and foremost a character study of this guy and the people he happens to cross paths with. It’s a testament to human empathy and the power of the human connection.”

Mr. McCarthy said he hardly knew where “The Visitor” would go when he first began exploring the issues it addresses. In fact, the story wasn’t originally set in New York, even though he knew he wanted to explore the idea of an unexpected friendship that leads a character to confront the issue of a immigration. Mr. McCarthy said he often would make the early-morning trek from his apartment in SoHo to his office on the Lower East Side with his dog, traversing Lower Manhattan while contemplating the fates of his characters. It only gradually dawned on him that New York would be the ideal setting for this modern American tale — the only hub through which such wildly different people could find themselves connected.

“I started doing research early on, before I even knew I would be making a movie about this,” the filmmaker said. “On a whim, I started volunteering for the Sojourners organization, working outside of Riverside Church. It’s this nondenominational outreach program where you visit the detention center in Elizabeth, New Jersey. I started doing that, staying connected to a detainee for six and seven months, and as you see this take its toll, you sort of get sucked into the issue.”

In short order, the plight of illegal immigrants, and America’s system of detention centers and deportation, came to the forefront of Mr. McCarthy’s world. He said he recalled seeing Ellis Island in a far different light — not merely as a tourist destination, but as a conduit through which so many immigrants hoped to lead American lives. And he started to see a different side of New York City that he wanted to commit to film.

“From the first day, I knew that what I wanted was an insider’s view of New York,” he said. “I wasn’t worried about sweeping cityscapes, but I wanted a more intimate feel, where you’re always at ground view, from beneath the buildings, where normal people actually live.”

He also knew that he wanted to tell the story through the eyes of someone like himself, someone who had never really considered the issue, but who was overwhelmed by the bureaucracy, confusion, and chaos of the detention system.

“Having Richard Jenkins really freed us up to tell things in a very personal way,” Mr. McCarthy said. “Many people recognize Richard, but he’s not someone who makes people stop and stare on the streets, so we could film right out in the middle of the daily activity, and he crafts such a subtle performance here, as he slowly comes to care about these people and their increasingly hopeless situation.” Mr. Jenkins’s performance, much like “The Visitor,” is deceiving in its modesty, a quiet façade crumbling as the outrage mounts. And much like “The Station Agent,” which built to one triumphant moment of defiance, so does “The Visitor” slowly build to its apex of indignation.

“At a point, it stops being a political thing,” Mr. McCarthy said. “I had this discussion with my family, and my father read the script and said he’d like to come one day to visit the detention center. So he came with me, with no preconceptions, and he was startled by what he saw. That’s what this film is — an honest representation of a human experience that everyone should at least see once, so we at least know what’s going on.”

ssnyder@nysun.com