Set in the year 1894 and reaching into 1895 during the time of The Testament of Sherlock Holmes, the overarching plot is that a group of terrorists calling themselves the Merry Men are attempting to overthrow the government, and free the people of the United Kingdom from debt. The game features six separate cases, some of which are direct adaptations of original Sherlock Holmes canon by Sir Arthur Conan Doyle. Each case is self-contained and apart from in-game achievements, such as moral choices, do not relate to one another.
The majority of the game involves exploring crime scenes and examining clues. Once discovered, clues are added to a "deduction board", a gameplay mechanic which involves linking pieces of information together. It will lead to possible different deductions. Once deductions are connected together, player will have a full tree of deductions. Depending on how players interpret the clues, they will have different conclusions. Therefore, the player can fail or succeed in finding the culprit. Players also decide whether to absolve or condemn the criminal. The moral choice the player makes will influence the further gameplay. Each case will have 3-5 possible solutions; in total there will be 6-10 different endings for each case. In total, the game offers 14 investigation mechanics, including Sherlock Holmes' skill to deduce many details about someone's life simply by glancing at them or to imagine and reconstruct the course of event by carefully observing all the key details of a crime scene.
Source: Wikipedia, "Sherlock Holmes: Crimes & Punishments," available under the CC-BY-SA License.