Dead Reckoning — Susan Latour

Catherine Lakey, a chemistry professor, takes a walk along a Cape Cod beach on a foggy morning in early spring and disappears. . .Local police uncover only her sandal buried by the tide along the shore.

The police investigation presumes that Catherine, a private woman, committed suicide, but after searching through Catherine's beach cottage, her niece Nancy is less than convinced. She has come upon a clue so subtle that only she could understand its meaning. . .a jar of marmalade, a nearly imperceptible disruption in her aunt's ordered life which suggests that Catherine Lakey is missing by her own design--not dead. Even with the small reassurance of marmalade, nancy is still left to decipher where her aunt has gone and why.

Nancy soon learns that little is arbitrary in her aunt's disappearance, and that the tiny clues left behind point to more than her aunt's whereabouts. Together with the begrudging assistance of Frank Simco, a concerned colleague of Catherine's, Nancy takes on the intricate work of locating her aunt. They quickly find themselves entangled in far more than a search for a missing person when a friend of Catherine's is murdered and they begin to find indications of an international conspiracy.

Nancy and Frank have charted a course far more dangerous than the harmless jar of marmalade ever could have indicated. They have charted a course of Dead Reckoning.