Charles Finch - A Stranger in Mayfair (Charles Lenox Mysteries, Book 4)

Returning from a continental honeymoon with his lifelong friend and new wife, Lady Jane Grey, Charles Lenox is asked by a colleague in Parliament to consult in the murder of a footman, bludgeoned to death with a brick. His investigation uncovers both unsettling facts about the family he served and a strange, second identity that the footman himself cultivated.