Clocking in at 55 minutes, Gian Carlo Menotti's opera "A Bride From Pluto" ends before the fat lady sings. Those adults who wait at the Kennedy Center Terrace Theater for the proverbial plump one will be sorely disappointed. The children attending this seventh annual "Imagination Celebration" production, however, witness an even more remarkable specimen of heavenly pulchritude: a queen from the skies who looks like a pinball machine and sings--in English!--like an angel.

Menotti's one-act work is written specifically for young people, whose attention spans are fallible. The composer notes three infallible ingredients for holding children's interest: action, music and pagentry, all in merciful abundance.

This most accessible opera concerns an extraterrestial's visit to a small planet from an even smaller one. The Queen of Pluto, a spacey wench big of hip and small of heart, decides to take a husband. Scanning the universe, she chances upon Billy, a tailor's son, leading a sew-sew life of hems and few haws.

Billy is bored; he wants to be a king. The queen jacks up the price of Billy's acceptance of her princely offer of marriage: After taking inventory of Billy's bodily parts, she insists that his heart be removed and replaced with a plastic machine. Billy is solar perplexus; without his soul, he would die.

Billy's earthly fiance'e, no dummy she, plans Billy's escape--while the queen is away, she substitutes a mannequin for Billy. Will the queen be successfully stiffed?

Baritone Nicholas Karousatos as Billy is superb. His acting talent is as large as his cavernous voice. Pamela Hinchman's Queen of Pluto (she originated the role) can hardly be improved--her soprano part drips with honey and vinegar. Robert Keefe as the tailor, Dana Krueger as the mother and Camille Rosso as Rosie are uniformly excellent in their supporting roles.