The Seven-Per-Cent Solution: Being a Reprint from the Reminiscences of John H. Watson, M.D. is a 1974 novel by American writer Nicholas Meyer.
It was published as a "lost manuscript" of the late Dr. John H. Watson and was made into a film of the same name in 1976.
Part 1: The Problem
An introduction states that two canonical Holmes adventures were fabrications. These are "The Final Problem", in which Holmes apparently died along with Professor James Moriarty, and "The Empty House", wherein Holmes reappeared after a three-year absence and revealed that he had not been killed after all. The Seven-Per-Cent Solution's Watson explains that they were published to conceal the truth concerning Holmes’ "Great Hiatus".
The novel begins in 1891, when Holmes first informs Watson of his belief that Professor Moriarty is a "Napoleon of Crime". The novel presents this view as nothing more than the fevered imagining of Holmes' cocaine-sodden mind. Moriarty was in fact the childhood mathematics tutor of Sherlock and his brother Mycroft. Watson meets Moriarty, who denies that he is a criminal and reluctantly threatens to pursue legal action unless the accusations cease. Moriarty also refers to a "great tragedy" in Holmes' childhood, but refuses to explain further when pressed by Watson.
The heart of the novel consists of an account of Holmes’ recovery from his addiction. Knowing that Sherlock would never willingly see a doctor about his addiction and mental problems, Watson, Mycroft, and Moriarty trick Holmes into traveling to Vienna, where Watson introduces him to the psychiatrist Sigmund Freud. Using a treatment consisting largely of hypnosis, Freud helps Holmes shake off his addiction and his delusions about Moriarty, but neither he nor Watson can revive Holmes’ dejected spirit.
Part 2: The Solution
What finally revives Holmes is a new mystery. Freud introduces Holmes to a catatonic young woman who has been hospitalized after a suicide attempt. Under hypnosis, she claims to be Nancy von Leinsdorf, the American wife of the recently-deceased Baron Karl von Leinsdorf. Holmes notices signs of recent imprisonment, but the woman cannot provide more information. Freud learns that the old Baron von Leinsdorf was in fact a German, possessing one of the largest weapons manufacturing empires in that country. His first marriage had produced only one heir, Manfred, a young man with an unsavory reputation who was active in right-wing circles. His second marriage, to Miss Nancy Osborn Slater, had taken place just two months before his death. Holmes, Freud, and Watson visit the Vienna Opera to make inquiries about the young Baron von Leinsdorf; to their surprise, he appears in person with a different woman claiming to be his stepmother.
Holmes fears the signs point to an impending European war, with millions of lives at stake. Holmes and Watson take the catatonic woman to the Leinsdorf mansion. As they arrive, Holmes recognizes Alfred von Schlieffen, the head of the German military, as he departs the house. Inside, they are presented to the Baroness von Leinsdorf, who immediately tells them that the catatonic woman is her former maid, Nora Simmons. She claims that Nora disappeared shortly after her husbands' death, and asks that Holmes leave her in her care. Holmes politely refuses, saying that Nora is being treated by Dr Freud. After they leave, he informs Watson that the baroness is an imposter, and that "Nora" is the real baroness.
Holmes and Freud discuss the political situation in Europe, particularly with regards to the German Kaiser, who has a pathological obsession with military strength. Holmes suggests that the old baron had come to regret his role in manufacturing arms. He had married Miss Slater, a Quaker, and re-written his will leaving his factories to her with the intent she should dismantle them. However, his son Manfred had learned of his intentions. Using his connections in right-wing circles, he had arranged his father's death to preserve his fortune and prevent the new baroness from dismantling a critical part of Germany's war machine. He had then kidnapped his step-mother and arranged for someone else to play her part.
Word soon arrives that the baroness has been kidnapped again. Holmes realizes that the baron is taking his stepmother back to Germany, and that they must catch him before he crosses the frontier. After a breakneck chase, they catch up to the baron's train. A fight ensues between Holmes and his foe, which ends in the baron's death. They find the real baroness locked in a trunk. The false baroness is also found, and revealed to be an actress named Diana Marlowe, whom the young baron had seduced in Berlin. Embarrassed, the German and Austrian governments cover up the affair and swear all the participants to silence; Watson reluctantly agrees out of consideration for Dr Freud. However, Holmes remarks that they have succeeded only in postponing a conflict, not preventing one, and He predicts the German government will use the baroness' mental state to assume control of her late husband's munitions empire.
One final hypnosis session reveals a key traumatic event in Holmes' childhood: his father murdered his mother for adultery and committed suicide afterwards. It was Moriarty who informed Holmes and his brother of their deaths, and his tutor then became a dark and malignant figure in his subconscious. Freud and Watson conclude that Holmes, consciously unable to face the emotional ramifications of this event, has pushed them deep into his unconscious while finding outlets in fighting evil, pursuing justice, and many of his famous eccentricities, including his cocaine habit. However, they decide not to discuss these subjects with Holmes, believing that he would not accept them, and that it would needlessly complicate his recovery.
Watson returns to London, but Holmes decides to travel alone for a while, advising Watson to claim that he had been killed, and thus the famed "Great Hiatus" is more or less preserved. It is during these travels that the events of Meyer's sequel, The Canary Trainer, occur.
- The Seven-Per-Cent Solution was followed by two other Holmes novels by Meyer, The West End Horror (1976) and The Canary Trainer (1993). A third sequel, The Adventure of the Peculiar Protocols, was published in 2019.
- In the novel, Watson claims that several of Conan Doyle's canon short stories are forgeries, specifically "The Lion's Mane", "The Mazarin Stone", "The Creeping Man", and "The Three Gables".