A first novel by lyricist and songwriter Sager, having to do with sour notes and final harmonies in the life of a career woman who's a name in pop-psychology, and her cheerfully dying mother (a pale echo of Auntie Mame). Also chiming in are: a glittery model/movie star; a dull couple with a lousy kid, and another writer/therapist who pushed love. Unfortunately, Sager neither shades in the stereotypes nor bums them with satiric acid. It's all rather flat. Katie Fielding's speciality is ""Mothers,"" and as writer, lecturer, etc., she's really big time. (The story opens with a cheapie come-on as, on air, Mike Douglas ""thrusts his phallic-shaped mike into the questioner's face."") Katie thought she had rid herself of her own mother, Lady Trace Landamere (the title from Trace's third husband), deciding that mother Trace's manipulation of her throughout the years was ""toxic."" But now Trace is back in Katie's life, since Trace has been given but a few months to live. With her small dog, Fred, in tow (Fred, probably the most appealing character, will inherit a mansion), Trace arrives in Manhattan to drive waiters wild, shimmer in dazzling outfits and clouds of cigarette smoke, and give a ""family"" party. Among the guests: Katie and Peter, the latter Trace's lover and Love-therapist; Katie's pal, the stunning actress Rebecca, who adores Trace; Trace's son Richard's wife, Ellen, with horrid brat Joshua; and a doctor and lawyer, both of them Trace's flirtees and friends. There are family slides (until Joshua smears the projector); Trace's will is read; and Trace produces a surprise dependent. Rage and chaos all around, but happy change is in the wind, and of course there's that airport scene before Trace takes off forever to that great Place in the sky. Lots of high-style clothes, appointments and pseudo-smart talk with a heavy-handed humor. But the author's name and video-exposure should keep this moving.