The plight of the homeless is not the most popular subject on prime-time entertainment. Television normally prefers uplifting and inspirational situations. One of the few television movies to cope with the homeless featured a feistily cute Lucille Ball as a bag lady. Among the weekly series, the subject has been broached at least occasionally on ''Beauty and the Beast,'' which describes itself as a ''contemporary fable.'' A certain distancing is necessary.
All of which makes tonight's episode of ''The Equalizer'' - on CBS at 9 - considerably more ambitious than usual. The hero of this weekly series is a suave vigilante named McCall, a former United States intelligence agent who now devotes himself to helping ordinary people. Going out after everybody from street thugs to corrupt politicians, McCall is the answer to a paranoiac's dream. He is played with courtly aplomb by the British actor Edward Woodward who, having had a heart attack last year, is a touch subdued these days but no less effective.
This evening McCall comes face to face with New York's homeless. It starts casually enough when a street panhandler asks him for a dollar. The man says: ''Walk me to the pizza place. I swear to God I'll get something to eat.'' McCall hands him $20. This is, after all, still television entertainment. Soon, however, McCall gets a call from a young boy named Billy (Matthew Stamm), who has seen the Equalizer's standing newspaper ad offering help to the needy. Billy's father (Michael Rooker) cannot find work as a machinist (''Now everything's made in Korea,'' Dad explains). The boy's mother is pregnant and, topping things off, the family van, containing his father's tools, has been stolen. The family has been evicted for being behind on the rent and is now being shunted by social workers to a welfare hotel near Times Square.
The story has become horrifyingly familiar over the past few years. In order to get resettled properly, which would include a month's rent and a month's security in a price-inflated market, the family would need at least $2,000. Obviously lacking that, they are placed in a dingy and dangerous hotel whose landlord gets up to $3,000 a month for their rat-infested quarters. In a neat scam, this television family is offered $500 a month by a threatening hoodlum to move out of the hotel and let the landlord keep them on the books.
The landlord in this instance is finally revealed to be a Mr. Amar (Michael Lerner) who, in a pronounced Middle Eastern accent, argues that his protesting tenants are the real criminals. ''They live off the state,'' says Amar indignantly. ''Sir,'' responds McCall, ''you are an atrocity.'' Fortunately, these television victims have the Equalizer to set things right, and viewers are given their inevitable moment of comfort when McCall announces that ''I'm about to make things very unpleasant for Mr. Amar.'' We know that at least this one family will be plucked from the brink of disintegration.
But Robert Eisele's script digs a bit deeper, attempting to get to not just the homeless but society's attitudes toward them. Needing assistance, McCall calls up his young friend Kostmayer (Keith Szarabajka). He agrees to help but, as a ''regular working-class guy,'' is not terribly sympathetic to problems of the homeless. His folks were never on welfare. Kostmayer declares: ''In America, of all places, people take care of themselves.'' McCall no longer buys that. ''This country has changed,'' he says, ''just look around you.''
Directed leanly yet pointedly by Tobe Hooper (''Poltergeist''), this episode of ''The Equalizer'' is tough, refusing to let anybody off the hook easily. Even as the relatively happy ending unfolds for this one white family, McCall looks over at the entrance to the rundown hotel and watches the impassive face of a black youngster. The face has been drained of hope. McCall looks profoundly discouraged.