It is all so perfectly spooky, and like any good tale of covert operations it is incredibly complex. So "Hot Shells" -- U.S. Arms for South Africa," a new investigative documentary to air tonight at 10 on Channel 26, takes a good 60 minutes to build its case:

Not only did a U.S. firm secretly supply high-powered artillery projectiles and equally high-powered technology to embargoed South Africa during the late 1970s, but -- and there's the clincher -- the U.S. government knew about this illegal activity and helped out.

There's extensive, sometimes numbing documentation, and most of the case seems solid, when reporter Jack Cole appears in front of the White House to offer the conclusions of this "World Special Report" by Boston's WGBH-TV.

"CIA operatives helped the Afrikaaners find the [supplier]," Cole tells us. Defense Department and State Department officials helped with the manufacture and even the shipment of the weapons.

"There are only two possibilities. Either these men of high rank in government where rogues off on an escapade of their own, or they were following orders from even higher -- orders to subvert the laws and policies of their own -- our own -- government . . ."

Wait a minute! Let's have a replay. That's important stuff about the CIA and State and Defense, but what's this about "only two possibilities"? cDid they get the orders or didn't they? Who gave them?

And why is this man standing in front of the White House? Do you suppose Jimmy Carter knew all about this? Do you suppose he gave the orders?

Who knows?

The producers of "Hot Shells" elearly do not, and they present no proof to back up such a contention.

Instead, they take advantage of an awesome power that television, more than any other news medium, possesses, the power to make the viewer believe something without actually having to prove it. One picture is worth a thousand implications, whether they hold, true or not.

There is little doubt that Spaces Research Corporation supplied South Africa with more than 50,000 rounds of highly sophisticated 155 mm artillery shells through a complicated cover arrangement on the Caribbean island of Antigua. That much was established in an earlier WGBH documentary and several others news reports.

In this new film, WGBH has managed to find CIA-connected arms dealer Col. Jack Frost, interview him, and establish that after he initiated contacts between South Africa and SRC, he dropped out of the deal and warned the State Department of what was going on.

"Hot Shells" also establishes such subsequent peculiarities as the Army's sale to SRC of 50,000 "rough forgings" -- not-quite-complete 155-mm shells -- without the normally requisite stipulations about who wanted them and for what. The Pentagon approved the deal in a record-breaking four days. a

The State Department then allowed the "rough forgings" to be shipped out of the country wothout the licensing normally required for arms because, supposedly, they did not really resemble munitions.

In this instance, a picture of the unmistakably projectile-like form of a "rough forging" really is all that's needed to suggest a remarkable blindness on the part of State.

SRC invoices are used to show how aadvanced technology was supplied -- along with the shells -- to allow South Africa to develop "in record time" some of the most effective artillery in the world.

The facts were quite good enough. There was really no need to imply any more.

On the other hand, for such a documentary there is a need to go to the places where the important events took place, and that far the producers of "Hot Shells" either would not go or could not afford to go.

Instead, they have borrowed a great deal of footage from an apparently better-funded BBC documentary on the same subject. They make extensive use of stock footage from film libraries. Time and again they resort to stills of key characters or, worse, their own reporters flipping through stacks of documents. Documents are great for reporting, interesting to read, but mightly dull to watch.

In the end, what could have been a fascinating and provocative documentary too often winds up seeming nothing more than an aggregation, quite literally, of cheap shots.