``Are you the editor?'' the hit man asks, and seconds later Beau Paxton, leaving Le Club in West Los Angeles with his roommate and ``uncle'' Norton Birdwell, is the late editor of Manor House, that paean to upscale design and unfettered consumerism. Manor House publisher Seth Rupert, unimpressed by the LAPD's interest in Birdwell as Beau's quarreling lover and insurance policy beneficiary, asks Pierpont Tree III, the oldest- money private eye in the L.A. directory, to look into the case in his inimitably civilized way. So Pier and his inamorata, lovely retired actress China Carlyle, hit the mean streets, attending an amusingly bitchy party for a sultan who can't imagine why Liz Taylor and Madonna haven't shown up, gathering information from gossipy lovers and artists and interior designers, and eventually giving due weight to the fact that Seth's partner and twin Jonas is deeply in debt to a shady New York investor who's determined to buy Manor House and ship his hideous wife out to the coast to run it and stay out of his hair. Most of the characters, though, rise above the violence into an ethereal region of tasteful fashion, aimless chitchat, and brand-name product placement, as if they were in a Dominick Dunne screenplay with its gilded pages shuffled into random sequence. At the fadeout, the triumphant lovers seem destined for further action, just like Nick and Nora. But Architectural Digest editor Rense's first mystery is more likely to whet your appetite for Robert B. Parker's first book on interior decor.