The sweet-natured and honest Brother looks like an ordinary African American man, distinguished only by his being mute and - although other characters in the film never see them - his feet, which each have three large toes. Upon arrival in Ellis Island, the Brother displays psychic powers, being able to hear the experiences of the immigrants that came before him. He is able to regenerate a foot that he lost after crashing in the ocean, perhaps to a shark bite. The Brother also has telekinetic powers but, unable to speak, he struggles to express himself and adjust to his new surroundings, including a stint in the Job Corps at a video arcade in Manhattan.
Repeatedly, people ask him where he is from. He points his thumb upwards, which many take to mean that he comes from Upper Manhattan.
The Brother has escaped enslavement on the planet he comes from. This is made evident in the film when he is in a museum with a young boy. He points to an illustration, displayed in the museum, depicting an enslaved African American who is running away, and then points to himself, indicating a similarity. He even frees a dog on a busy street from its tether, not realizing that it was leashed for a reason.
He is chased by two white Men in Black (David Strathairn and director Sayles himself); Sayles's twist on the Men in Black concept is that instead of government agents trying to cover up alien activity, Sayles's Men in Black are also aliens, out to re-capture "The Brother" and other escaped slaves and bring them back to their home planet.
The Brother meets a variety of people, including the black habitués of Odell's bar, the nice Mrs. Carter who gives him a place to stay, a card trickster on the subway, a couple of young white Midwestern men who wander by accident into Odell's and attempt to befriend him by talking about Ernie Banks, street junkies who rob him and injure him (he is able to heal himself at once), and a friendly cop who is new to Harlem.
Captivated by posters for a black singer, Malverne, he earns the money to attend one of her singing gigs and has a tryst with her.
Seeing some dead junkies on the street, he samples the remainder of their product and hates the result. After this, the movie changes into a darker, if not entirely dark, tone. He recognizes some graffiti as language from his own planet, but the Men in Black recognize it, too. In his own bizarre and alien way, he watches the drug dealers and teaches one of the top honchos a lesson.
The Men in Black capture him, briefly, but they find themselves facing a neighborhood of blacks who support the Brother. Cornered, they destroy themselves. After taking the A train, the Brother turns and smiles into the camera.
While the Brother does not speak, much of the film consists of other characters blabbing on to him, seemingly unaware, or uncaring of the fact that he does not respond. This can be interpreted as a commentary on how self-absorbed people are.
Sayles describes this movie as being about the immigrant experience of assimilation. He spent part of his MacArthur Fellows "genius" grant on the film, which cost $350,000 to produce.
Variety called it "vastly amusing but progressively erratic" film structured as a "series of behavioral vignettes, [many of which] are genuinely delightful and inventive"; as it continues, the film "takes a rather unpleasant and, ultimately, confusing turn." Vincent Canby called it a "nice, unsurprising shaggy-dog story that goes on far too long" but singled out "Joe Morton's sweet, wise, unaggressive performance." Roger Ebert gave the film three-and-a-half stars out of four, saying "the movie finds countless opportunities for humorous scenes, most of them with a quiet little bite, a way of causing us to look at our society", noting that "by using a central character who cannot talk, [Sayles] is sometimes able to explore the kinds of scenes that haven't been possible since the death of silent film."
The A.V. Club, in a 2003 review of the film's DVD release, says the film's superhero scenes are "often unintentionally silly, but again, Sayles shapes a catchy premise into a subtler piece, using Morton's 'alien' status as a way of asking who deserves to be called an outsider in a country born of outsiders"; commenting on the DVD, they note its "marvelous" audio commentary track by Sayles, "who moves fluidly from behind-the-scenes anecdotes to useful technical tips to unpretentious dissections of his own themes."