"The Frye twins are approached by Henry Raymond, a penny dreadful writer, as well as his follower, a young Arthur Conan Doyle. They team up to investigate a series of murders across London, visiting crime scenes, gathering evidence, interviewing witnesses and suspects, and ultimately solving the crimes by accusing the true perpetrators."
Source: Wikipedia, "[en.wikipedia.org/wiki/Assassin%27s_Creed_Syndicate%23The_Dreadful_Crimes Assassin's Creed Syndicate]", available under the CC-BY-SA License.