Third in a series adopting the era, voice, and persona of Jane Austen (Jane and the Man of the Cloth, 1997, etc.). Living in Bath with her parents and sister Cassandra, Jane is asked by old friend Lord Harold Trowbridge (known as the Gentleman Rogue) to keep an eye on his niece, Lady Desdemona, who's left London for Bath, busily evading the attentions of the Earl of Swithin. Thus Jane is present at a costume ball given by Desdemona's grandmother, the Duchess of Wilborough, attended by all of Bath's high society and by members of the local Theatre Royal: manager Richard Pascal, along with leading actors Hugh Conyngham and his sister Maria. It's Desdemona's brother Simon, the Marquis of Kinsfell, who, in an anteroom to the ballroom, finds Pascal's stabbed body, removes the dagger, and hears Pascal's last word--``Maria.'' He's also found, and concealed, the miniature painting of an eye, left on the body. Magistrate Wilberforce Elliot wastes no time in arresting Simon for the killing, and while Simon languishes in jail, his execution almost certain, Lord Harold and Jane set about finding the true murderer. This is no mean feat, for the puzzle's roots are deep in the past, and, as it transpires, Pascal was an innocent victim of the masquerade's duplication of costumes. Barron's re-creation of the speech, manner, and innermost feelings of her heroine is uncannily on target, but the byzantine plotting and huge canvas of characters--some pedestrian, some intriguing--will be best appreciated by patient Austen aficionados.