Off Broadway Theater seems to have struck gold with its latest offering. "Once Upon A Mattress," a vaudevillian musical based loosely on the fairy tale "The Princess and the Pea," is a nice choice for the troupe of slapstick performers. If only they lost the minus-track and played all of the musical numbers live, this would be near-perfect.

As is, it's enormously entertaining. Steve Harmon begins the show as a traveling minstrel. Although he strums a lute, what comes out is a synthesized piano and string arrangement that doesn't quite fit. However, the ballet is charming and introduces the play perfectly.The minstrel arrives in court just as the queen is turning down the twelfth candidate for princess.

Because a law forbids anyone in court to marry before the prince, the courtiers are extremely, well, frustrated. Throughout the show, they play this to the hilt.

The queen, played by Alison Jensen, refuses her son's suitors out of a combination of over-protectiveness and a reverse-Oedipal complex. Jensen is delightfully overbearing and malicious.

Russell Peacock plays the mute king hilariously. The king communicates through a manic series of charades and exaggerated facial expressions, and Peacock displays amazing concentration and comic timing. He never breaks character nor does his energy slacken.

As the jester, Zac Zumbrunnen often has to interpret for the king. He also shares many comic moments with Jesse Dolce as the egocentric wizard. Harmon, Dolce, and Zumbrunnen combine for one of the play's funniest scenes.

A subplot with Sir Harry and Lady Larkin is handled well, with stand-out work by Ryan Poole and Leslie Heath. Poole's vanity approaches villainy and Heath is a spunky maiden in distress.

Laura Bedore, who directed the show, also steals it as "Fred" the prospective princess. Her character is adorable and funny, especially in the musical numbers such "Shy" and "Happily Ever After."

Perhaps the strongest character musically is Dave Hunsaker as Prince Dauntless. He shines when singing "I'm in love with a girl named Fred" and attempting to have a "Man to Man Talk" (another song) with his mute father.

He brings an engaging innocence to his character.

Choreographic high points include "The Spanish Panic," "Very Soft Shoes" and "Normandy," although the latter suffered on opening night from a lack of syn-chro-nic-ity with the minus track. The numbers which Dorothy Keddington plays live on keyboard are best because the singers know she will stay with them.

For pure entertainment, it's hard to beat this show's physical and verbal comedy, clever music and lyrics and a happy ending.