1888: Dr. John H. Watson, Army Corps surgeon turned colleague of the celebrated consulting detective Sherlock Holmes, decides not to assist in future cases as he is engaged to Mary Morstan. 1926: Mary Forrester discovers her mother's diary, covering the years 1889 to 1893 — her marriage to Watson. What occurred in those years? How was the quintessential male friendship of Holmes and Watson seen through a woman's eyes? How stable was a marriage where Watson was liable to abandon Mary at Holmes’s summons? Who, ultimately, was Mary Morstan — a figure seldom referred to in Arthur Conan Doyle’s sixty Holmes stories? This blend of fact and fiction sheds light on a virtually unexplored dimension of the Great Detective’s exploits. It is a perspective Sherlock Holmes —who elevated “true, cold reason … above all things” - would probably not appreciate. But for all its warmth and irrationality, there is just as much truth in the heart.