Charlotte and Mrs. Watson receive a request for help from Lady Ingram, wife of a very close childhood friend (and perhaps more?) Lord Ingram Ashburton, or "Ash" to his close chums. Lady Ingram's situation involves Myron Finch, a young man she once loved. They parted because her parents deemed him unsuitable to marry, but they made a pact: once a year at 3 p.m. on a scheduled date, they are to walk by the Albert Memorial. A glance as they pass each other will ensure each is alive and well. Lady Ingram then married Lord Ingram for his fortune, but two children and six years later, they are very unhappy. They barely acknowledge each other in the privacy of their home. Lady Ingram turns to Holmes for help when Myron doesn't show up for their annual meeting. The other dilemma: Myron Finch is Charlotte's illegitimate brother. Lady Ingram pleads for their help to find Mr. Finch, and so the adventure begins.

Sherry Thomas writes a sterling historical mystery and does an interesting job dealing with gender reversal. A CONSPIRACY IN BELGRAVIA begins as a missing person case but evolves quickly into a mystery with murder, lies, secrets, and betrayals. Cryptic codes, family and a surprise marriage proposal to Charlotte from Lord Bancroft, older brother of Lord "Ash" Ingram, adds zest to the plot until the mystery is solved. A clear message at the end that there will be a sequel. Soon, I hope. Great read. As a big fan of historical mysteries, I look forward to more in this series!