The heroics of the line, The Show Must Go On, often muffle entirely the foolhardy aspects of the sentiment. There are times when the star is better off in her dressing room nursing a broken heart or a case of mumps. There are even times when an entire show could be discreetly removed from circulation and, by withdrawal, best serve the cause of theatre tradition. Producer Elizabeth Miele and her cast have a game battlecry in the title On With the Show; by retreating quickly they might live to fight another day.

Miss Miele's folly is compounded, and more understandable, for she also wrote the show's lyrics. They are fine PTA Musicale words, rouged up with four-letter expletives for their new surroundings. Numbers like "Dynamic," "The Wide Open Space," and "Nevada Hoc Down" could undoubtedly finance many an encyclopedia and blackboard for some grade school.

The composer, Frederico Valerio, has avoided the pitfall of patterning his score after successful musicals. There is nothing in On With the Show which sounds like Guys and Dolls, The Pajama Game, or Can-Can. A steady radio listener, however, might recognize the Ajax commercial or the overture to a toothpaste jingle.

The tip-off to the whole show comes in the Second Act when a man named Paul Valentine skips around the stage singing "My Fatal Charm." That this number and Mr. Valentine do not have charm and, indeed, are almost loathsome is not a disaster. But Miss Irra Petina, the show's leading lady, is likewise unblessed. Along with her strong voice, Miss Petina projects a chill which seems to come right from the heart. Although even a Shirley Booth couldn't salvage On With the Show, Miss Petina estranges the audience just a bit further. Her co-star, Robert Wright, plays a Nevada banker who is financing the stars of a stranded opera company. He sets Miss Petina up in a beauty emporium, falls in love with her, and--worst of all--sings about it.

After apportioning the blame impartially among the book, score, and cast, the playgoer can relax for a minute and recall the dancing. Don Driver and Diana Drake are no Champion, but do belong on the stage. When On With the Show moves at all, it is on their feet.

Equally inventive is the staging, with outsized venetian blinds manipulated like a kaleidoscope to vary the settings and change the scenery. Stagecraft, however, can only do so much: the orchestra plays, the screens shift and slide, the old scenery is miraculously whisked away within a second, and then back you are again, stranded in Virginia City with Irra Petina, Paul Valentine, and Miss Miele's lyrics.