THE BROTHER From Another Planet" is a brother from "Another World." Joe Morton, who plays twins on the popular soap, enters a new dimension as the eloquent silent star of John Sayles' unconventional and compassionate outer- space spoof.

The Brother, a mute black alien with big rubber feet and a socket in his side, looks like a street person wearing something Mr. Spock gave to Goodwill. He crashes on Ellis Island, where he touches the walls and hears the whispers of other immigrants. Quickly, he regrows a missing foot, hops a tug up the Hudson and arrives at an even more haunted place called Harlem.

Locals in a neighborhood bar -- Smokey, Fly and Odell -- decide that he's either deaf, crazy or a wino -- and find him a job fixing video games and a place to stay. Like E.T., The Brother can heal things -- skinned knees or broken computers. But he can't go home; he's trapped in a society where he has to learn the ropes, an outsider everybody thinks is in.

"At first, he doesn't know whether the dog is walking the person or the person is walking the dog," says Sayles, who directed, wrote, edited and costarred. He and David Strathairn play space slavers who trace The Brother to the Harlem bar. They claim to be with Immigration, but their speech makes them sound like Jack Webb and the Coneheads. The locals -- a super comic ensemble -- are suspicious, but take it in stride: "White folks are getting stranger," is all Smokey says.

Later when a couple of yuppies from Indiana bound for a wine-and-cheese seminar lose their way and end up at the bar, well, nobody's surprised. And we see just how nervous they are out of their world. What seemed at first to be a throwaway scene soon fits the overall theme -- alienation, a Sayles favorite that prevails in "Lianna" and his other films, too.

The Brother also exposes the basics of bigotry, the misunderstandings among cultures that are exaggerated into racism, sexism and classism. Radios the size of suitcases are as unfathomable to him as they are to the grey flannel man. Drug dealers and the welfare system are even more perplexing, making strangers of those who should be at home in this strange land.

"The Brother From Another Planet" is brilliant science-fiction with a social conscience. It goes to worlds where men, some of them anyway, have never gone before. And all they really ever had to do was take the A-Train.