Holmes is asked to recover stolen submarine plans that could threaten national security. Solution: The plans were stolen by Colonel Valentine Walter, who intended to sell them to a foreign power. Holmes recovers the plans and Walter is arrested.

The Adventure of the Bruce-Partington Plans

A university lecturer asks Holmes to investigate after exam papers are tampered with, and he suspects one of his students. Solution:One of the students, Gilchrist, tampered with the papers. Gilchrist confesses and decides to leave the university to join the military.

The Adventure of the Three Students

A military officer is found dead, and his wife is the prime suspect. Solution: Holmes discovers that the real killer was a "crooked man," Henry Wood, who sought revenge for a betrayal in India that led to his physical deformity and ruined life.

The Adventure of the Crooked Man

Holmes receives a cipher message leading him to the murder of John Douglas at Birlstone Manor. The story involves secret societies and past crimes in America, with Douglas having fled a violent gang. Solution: Douglas faked his own death to escape the criminal gang seeking revenge for his betrayal. Holmes unravels the plot, revealing that Douglas was hiding from the Scowrers, a secret society from his past, and that he successfully eluded them until they tracked him down.

The Valley of Fear

Helen Stoner fears for her life after hearing strange noises in her house, similar to those heard by her sister before her mysterious death. Solution: Helen’s stepfather, Dr. Grimesby Roylott, trained a venomous snake to crawl through a vent and kill his stepdaughters to keep their inheritance.

The Adventure of the Speckled Band

Holmes is asked to verify a claim that three men with the surname Garrideb will inherit a fortune if they meet together. Solution: The scheme was a ruse by a criminal, John Garrideb, to lure a man named Nathan Garrideb out of his home so that he could steal valuable documents. The criminal is apprehended.

The Adventure of the Three Garridebs

Violet Smith seeks help when she notices a man following her on a bicycle during her weekly trips to the train station. Solution: Violet’s uncle was swindled by a man named Carruthers, who now wants to marry Violet. Carruthers’ accomplice, Woodley, kidnaps her, but Holmes and Watson rescue her.

The Adventure of the Solitary Cyclist

While on vacation, Holmes and Watson are drawn into the investigation of a burglary that escalates into murder. Solution: The murder was committed by the son of a local squire, who forged letters to cover up his theft of important documents. The squire’s son is apprehended.

The Adventure of the Reigate Squire

Holmes is targeted by Professor Moriarty, a criminal mastermind who seeks to kill Holmes before he can dismantle his criminal empire. Solution: Holmes and Moriarty confront each other at the Reichenbach Falls, where Holmes seemingly falls to his death, taking Moriarty with him. However, Holmes later reveals he survived.

The Adventure of the Final Problem

The mysterious disappearance of Mr. Garcia, who had been staying at Wisteria Lodge. Solution: Garcia was involved in a plot to overthrow a Central American dictator. Garcia was killed by his co-conspirators after they betrayed him.

The Adventure of the Wisteria Lodge