The quietest disappearance imaginable--a Connecticut chemistry professor fails to return from her vacation on Cape Cod--blossoms into international intrigue in this deftly understated first novel. The police in Cotchpinicut, Mass., think that finding Catherine Lakey's sandal washed up on the beach indicates that she never returned from her last swim. But her orphaned niece, Nancy Mulholland, arriving from the Midwest, finds too many false notes in Catherine's unexceptionable life to be convinced. Why did a man turning up months ago at Ruth Lakey's nursing home pass himself off as Catherine's brother, and why, when Catherine found out about her mother's visitor, did she ask the staff not to tell her niece? What's the meaning of the unobtrusive clues--a jar of marmalade, a telltale cookbook--Catherine has left behind at Cotchpinicut, clues that nobody but Nancy would notice? And why was Richard Weiss, Catherine's friend in Pittsburgh who promised to explain everything to Nancy, killed hours before she could reach him? Enlisting the reluctant help of Frank Simco, Catherine's dean, Nancy doggedly ties her aunt in to a government agency that's evidently found a way to carry out assassinations without leaving a trace. This end of the plot is standard espionage fare, of course; but the authors take such pains to set the hook--keeping close to Nancy's puzzled, quietly determined point of view for so long--that the James Bond heroics, when they finally come, seem like a natural outgrowth of the missing- relative story; and it's highly appropriate that the climax turns on questions of moral accountability, not the principals' personal survival. The Pelican Brief without all those killers skulking in the shadows--and with a far more likable, believable pair of heroines.