When Miss Catherine Kent's fiance Richard Montague disappears, she is distraught. Catherine sends for her beloved spinster aunt, Miss Dido Kent. But on the very day of Dido's arrival, a sinister discovery casts unwelcome suspicion on Richard's sudden absence. Long-hidden family secrets begin to emerge as Dido attempts to unravel the strange happenings. Dido uses her logical thinking to carve a swathe through the ulterior motives of the other guests. When she finally arrives at the startling truth, it is to change the lives of those involved forever. But will it be for better or worse, for richer or poorer, in sickness or in health?