Corporate shenanigans in the N.Y. advertising business--most of them hinging on the rise of the ""accidental woman,"" young Sara Vardon. Why accidental? Because, in the involving early chapters (which include grimly graphic brain surgery), timid, frigid copywriter Sara is operated on for a brain tumor--and, thanks to the surgeon's slip, she emerges from the hospital with a totally new personality: aggressive, sensuous, amoral. Medically possible? Well, sort of. But from that point on the new, improved Sara is a virtual non-character--unlifelike, unsympathetic--who can't hold this readable yet uncompelling novel together. She vows to somehow win back her lover--ad-agency biggie Rick, who returned to his estranged wife and child while Sara was in the hospital. She comes up with a supposedly brilliant (actually ho-hum) ad-campaign idea that brings in a big new client: Harry Dalton, boisterous and abrasive super-tycoon (airlines, movies, hotels). She uses this coup to rise in the agency (coached by Dalton, who's infatuated). And when Dalton decides to mastermind a corporate takeover of Sara's agency, forcing out agency founder Brooks Madden, Sara becomes Dalton's eager co-conspirator (and Barbados bedmate): Brooks is pushed into having the agency-corporation go public; Sara and another Dalton spy manipulate the board; greedy-stockholder pressures are applied; and Brooks (who's preoccupied with his rejuvenating love for a well-preserved movie star) is squeezed out, making way for a Dalton takeover. The scheme is finally foiled, however--thanks to Dalton's jealous secretary-mistress, who supplies distraught Brooks with evidence of the Dalton/Sara conspiracy. Somewhat less sleazy and violent than the run of glamorous boardroom/bedroom melodramas, this is serviceable commercial entertainment (especially for readers partial to drawn-out Wall St. manipulations); but it lacks the engaging characters, neat twists, and authentic details needed for top-drawer business/romance fiction.