Summary
The story begins with the detective Sherlock Holmes injecting cocaine into his system in a seven percent solution. His friend Dr. Watson frowns upon this and voices his concern. Sherlock has track marks running all along his arms.
Sherlock explains that he finds the cocaine helps him think, while Watson continues to disapprove. He worries that his friend's drug habits could lead to his mind being damaged, effecting the loss of his supreme detective skills.
Holmes then goes on to brag about his status as the only unofficial consulting detective in the world; in the same breath he declares his love for the simple fun of solving a mystery, rather than for any potential fame he might derive from his skills.
Sherlock reveals that while Watson has been publishing their cases, he has been working on his own writing–namely, enumerating 140 different types of tobacco ash and how to distinguish them. He also demonstrates his detective skills by deducing where Watson was that morning, despite it being an unplanned morning governed by whims.
Sherlock also demonstrates the difference between observation and deduction. He observed a reddish mold on Watson's shoes and knew which neighborhood such soil existed. From that he deduced the rest: his friend had gone to send a telegram based on the state of his desk and mindset this morning.
Watson puts his friend's abilities to the test with a watch that he recently received; Sherlock deduces that it recently belonged to his elder brother who started out life at an advantage but ended up broke and a drunkard. At that moment, as they are discussing it, they are interrupted by the appearance of Ms. Mary Morstan, who has a case for Sherlock to solve.
Mary explains that many years ago, her father disappeared on a trip. A few years later, an ad appeared in a newspaper asking for her address, which she gave, and ever since then, on the same day of each year, a rare and expensive pearl is sent to Mary. Then today, she received a letter asking to meet her and not to bring the police; Mary asks Watson to accompany her. He agrees.
Analysis
Sherlock ultimately dismisses his friend's concerns about his cocaine habits, as he values his own enjoyment and mental acuity now, over that which he might sustain later. Characterization reveals that Sherlock does not worry about the future too much, and is very arrogant and sure of himself.
Holmes shows that he is not above critiquing his friend's work, offering a few harsh words regarding Watson's publication of a story about their most recent case. Watson is a little piqued since his story was meant almost as a gift for Sherlock, to flatter and praise–but now he is being criticized for his efforts.
We learn even more about Holmes' characterization when we see how brusquely he treats the issue of Watson's destitute older brother. Holmes is very intelligent intellectually, but perhaps not very intelligent or in-tune with emotions and people's reactions to his words.
Mary is introduced to the reader with little description of her character, other than a mysterious background, but it is clear from the beginning that she has captured the heart and curiosity of Dr. Watson.
The reader has another chance to observe the deductive powers of Sherlock Holmes as he examines the letter that Mary received with his acute eye. He determines that it is authentic and that Mary and Watson should go to meet this mysterious person.
