Southwold Mystery — Suzette A. Hill

Rosy Gilchrist has been asked to accompany Lady Fawcett to visit Delia Dovedale, an old school friend in Suffolk and whom she hasn't seen for years. Rather reluctantly Rosy agrees to be her companion on this reunion jaunt. But on arrival at their hostess's house the two guests discover that things are far from normal, and find themselves plunged into a series of bizarre and sinister events.