Rose McQuinn followed her heart and married Danny McQuinn. However, Danny's work exposed him to many dangerous enemies and one day he disappeared from Rose's life altogether. Believing him to be dead, Rose returned to Scotland in order to start a new life. Three years have passed since then and she has fulfilled her ambition of becoming a "Lady Investigator, Discretion Guaranteed" and is about to marry D. I. Jack Macmerry. But pre-wedding jitters become the least of her worries when a nun from the local convent claims to have received a letter from Danny. Unnerved and determined to find out the truth before her wedding, Rose begins to investigate.