Imagine Barry Manilow cubed and there you have the Bee Gees, one of the more mystifying and discouraging entertainment phenomena of our discomaniacal times. When the three brothers Gibb (hence, "Bee Gees") sing together in their silly falsettos, you could swear you're hearing a trio made up of Minnie Mouse, Mr. Bill and The Fly.

The boys who made much of the music in "Saturday Night Fever" get their own "Bee Gees Special" on NBC tonight, at 9:30 on Channel 4. The producers offer them up as a holy trinity of vacuous diversion; the program is as horrible and fascinating as watching a hooked fish die on a boat dock.

Much of it consists of dreamily-creamily shot concert footage, in which the computerized Bee Gees oeuvre is continually accompanied by the crash of girls' screams upon the conditioned air. Watching this overwhelmingly ineffectual triumvirate loiter about the stage, one struggles for an adequate excuse for their popularity.

Perhaps we should take a cue from an old geezer in "The Rutles," a spoof on the career of the Beatles, who, asked to explain a pop group's success, replied, "I think it was the trousers." Bee Gee trousers are as seamless and tight as the singers are flavorless and cold; the special should have been subtitled, "The Secret Life of Pants."

It opens with a dramatization in black and white of the boys in their tothood, improvising a version of "Lollipop" ("Lollipop, lollipop, oh, lolly, lollipop") onstage at the Odeon theater in Manchester.

Then, slam, bam, special effects, we flash forward to the Bee Gees at the height of their renown today, as they sing one of the biggest of their big-big hits. Appropriately enough, this hymn to their own success is called "Tragedy."

In between a recital of other platinum monstros like "How Can You Mend a Broken Heart" and, inevitably, "Stayin' Alive," we get privileged glimpses behind the scenes. Well, not really behind -- more, just to one side of the scenes.

Glimpses of Bee Gees at work and play include a top-level discussion among them and their flunkies about which and how many logos should appear on their worldwide tour plane and lengthy deliberation about just where an explosion should go on a recording of "Tragedy." There are also interview snippets with David Frost, his unctuousness on overdrive for the occasion.

The most charitable thing to be said about these is that the Bee Gees come across as preening imbeciles.

David Frost also interviews that merchandiser of the ultra-mediocre Robert Stigwood, who talks about his little gold mine, the Bee Gees. By uncanny coincidence, the executive co-producers of this program are David Frost and Robert Stigwood. How they kept Robert Stigwood from also interviewing David Frost we will never know.

Bee Gees fans may be delighted by the merciless abundance of Bee Gees tunes on the special, but even they should be taken aback by the group's conspicuous lack of grace or generosity. Guest stars Willie Nelson and Glen Campbell are relegated to a brief stint as part of a chorus dominated by the Bee Gees. Even the Gibbs' own little brother Andy is all but elbowed off the stage by these sylphs as he attempts to sing his hit, "You Should Be Dancing."

Surely the flip side ought to have been "You Should Not Be Singing."

Onstage, the Bee Gees are surrounded by the usual rock camouflage of flashing lights and smoke bombs, and they are backed up by a huge orchestra. Without all that gimmickry, there would be no act. The Bee Gees are nothing, in triplicate. They are 99 percent production and one percent sheer gall. They are ideal entertainment for an age colored Clockwork Orange.

"The Bee Gees Special" is a sign of the times that points straight down.