"I never knew you had a brother, Howard," says Lady Cicely Waynfleet to her brother-in-law, Sir Howard Hallam, in the first act of CAPTAIN BRASSBOUND'S CONVERSION. And Howard answers (unpardonably): "Perhaps because you never asked me." It's like that all the way through three long acts: hack-work by a great playwright Shaw's intention, no doubt, was to present a series of unjust sentiments in elegant language, but all that he actually achieved was a preposterous plot, a smattering of coy jokes and wheezy epigrams, and a brace of cardboard characters (there's even a comic Cockney).

And yet, by some incomprehensible alchemy, the Summer School Players have been fired by this play to produce by far their best performance of either this or last summer. The Players, in fact, seem to enjoy themselves extravagently; they crack their dreary jokes with every sign of glee; manipulate a formidable number of accents and dialects with surprising confidence; and don't even slow down in the middle of the dialogue's horrible stretches of Moorish waste. They are themselves as funny as their play is tiresome.

A good deal of their inspiration, of course, must have come from Donald Soule's sets, which are so good as to merit mention before anything else. Soule's Moroccan garden and castle have a Mediterranean brilliance and intensity that make anyone on stage appear, inevitably, just a little more interesting than he could hope to be all by himself. It is a light which also shows off to good advantage Lewis Smith's handsome period costumes.

Then, too, the Players could never have gone very far without Joseph Everingham's briskly professional direction. The pacing is perfect, as it must be -- most of the lines haven't a glimmer of a chance unless they're ripped off as fast as humanly possible. At the same time, the staging is relaxed, assured, and deft: there is no stumbling, and little awkwardness.

Yet none of this top-flight technical assistance can by itself fully account for the inspiration of the Summer Player, many of whom have never been quite so good before. Take Joanne Hamlin, for instance. Her Lady Cicely is everything Shaw himself could have wanted from the part: she can completely silence the ditherings of male incompetence with a few words in her quiet, unruffled voice that can tolerate absolutely no nonsense. Demurely dominating, she establishes her pleasant despotism early in the first act, and it is subsequently never seriously shaken.

Or take Samuel Abbot, who has always enjoyed being insufferably English on stage, but who only just now as Sir Howard Hallam has achieved the appearance of an educated, nourished, pampered, brushed, and altered tomcat, Sir Howard, naturally, is one of Lady Cicely's first successful take-over bids, and Abbott succombs with just the proper air of well-bred petulance. Then there's Robert Chapman, who, as Captain Hamlin Kearney (an American naval officer devised to fill up the last act), suffers such an astounding sea change as to be almost unrecognizable. Kearney is the last of Lady C's successes, and when Chapman surrenders, you know she has conquered the salt-bitten gallantry of the entire U. S. Navy.

And two local comic geniuses, David Cole and Kenneth Tigar, mug their way through minor roles. Cole is the comic Cockney, and very much so; and Tigar's beatific moronic grin makes him much the most memorable of Captain Brassbound's crew. The Captain himself is, alas, not so memorable. Tom Griffin looks dashing enough, but his voice remains as flat and as blurred as ever.

It all seems almost too good to last, and certainly won't after Saturday night. Until then you have just six chances to see a first-rate show. I figure it will cost you only $9.00 to go all six times.