Mary Finch is a young woman of wit, courage, and straitened circumstances. When invited to meet her wealthy uncle and end a family estrangement, therefore, she sets off immediately for White Ladies, his estate on the Suffolk coast. Yet soon she is embroiled in an adventure beyond any she could imagine, for the year is 1795, and England is at war with Republican France. When she arrives at White Ladies she learns that her uncle has died, leaving behind evidence of a treacherous plot.