" The Last Case " was a mystery novel written by Christie of the United Kingdom. It told the story of a detective, Arthur Conan Doyle, who worked with Detective Moriarty to solve an unsolved case. Story summary: Moriarty was one of the most experienced detectives in Britain. He was proficient in a variety of criminal methods and was good at using psychology and social relations to solve cases. While investigating a bank robbery, Arthur Conan Doyle found a connection between Moriarty and the perpetrator and brought him into the investigation. As the investigation deepened, Moriarty's true identity was gradually revealed. He was suspected of plotting many crimes, and Arthur Conan Doyle finally solved the case with his wisdom and courage. In the novel, Moriarty was portrayed as an extremely intelligent and witty criminal genius. He was not only proficient in various criminal methods, but also good at using psychology and social relations to achieve his goals. His cleverness and methods made Arthur Conan Doyle feel very troublesome, but in the end, Arthur Conan Doyle defeated Moriarty through his cleverness and courage. Moriarty's character image was very distinct. His image was somewhat similar to Watson in Sherlock Holmes. They were both extremely intelligent and witty criminal geniuses, but the difference between the two was that Moriarty's criminal activities were illegal, while Watson's were legal. Although Moriarty's criminal behavior was chilling, it also reflected the distortion and darkness in his heart. He was willing to sacrifice others for his own benefit. " The Last Case " was an excellent detective novel. Through the complicated storyline and Moriarty's character image, the readers deeply experienced the joy of detective reasoning. The image of Moriarty as a criminal genius also had a certain practical significance, reflecting some of the real problems in society.