Publication date: 1905 (as part of the collection The Return of Sherlock Holmes)Setting: London, EnglandMain characters:Sherlock Holmes: The world's most famous consulting detective.Dr. John Watson: Holmes's friend and chronicler.Mycroft Holmes: Sherlock's older brother and a high-ranking government official.Arthur Cadogan West: A young clerk who steals the submarine plans.Plot: The British government entrusts Mycroft Holmes with top-secret plans for a new submarine. The plans are stolen from a government office by Arthur Cadogan West, who is later found dead near a train station. Mycroft seeks Sherlock's help in recovering the plans before they fall into the wrong hands.Themes: Espionage, patriotism, betrayal, the importance of secrecyMemorable quotes:"There are no crimes which are commonplace. If we all acted on that belief, the whole detective force might be disbanded tomorrow." - Sherlock Holmes"The game is afoot!" - Sherlock Holmes"Elementary, my dear Watson." - Sherlock Holmes (although this famous line is not actually spoken in this story)The Adventure of the Missing Submarine Plans is one of the most famous Sherlock Holmes stories, and it has been adapted for film, television, radio, and theater many times. It is a suspenseful and exciting story that showcases Holmes's brilliant deductions and Watson's loyalty and friendship.Here are some additional details about the story:The submarine plans are for a revolutionary new design that would give the British navy a significant advantage over its rivals.West is motivated by patriotism and a desire to help a foreign power that he believes is more deserving of the technology.Holmes and Watson must not only find the plans but also determine who West was working for and what their intentions are.The story is full of twists and turns, and it keeps the reader guessing until the very end.