With London's streets deserted, a young flower girl is murdered. But why was she out so late on the foggiest night of the year? The inspector has no where to even begin looking for a suspect. However Mrs. Jeffries, his housekeeper, is even more accomplished at detection than she is at household management.

This charming series of Victorian murder mysteries features mild-mannered Inspector Witherspoon of Scotland Yard and, more importantly, Mrs Jeffries, his housekeeper. A policeman's widow herself, her quick wits allow her to nudge the Inspector in the right direction to solve the crime.