Sherlock Holmes and Dr Watson's adventures in 21st Century London. A thrilling, funny, fast-paced contemporary remake of the Arthur Conan Doyle classic.

The update maintains some traditional elements of the stories, such as the Baker Street address and the evil Moriarty. Although the events of the books are transferred to the present day, existing elements are incorporated into the new characters to "ground the forthcoming tales in reality, and appease ardent fans of the classic tales"; for example, Martin Freeman's Watson has returned from military service in Afghanistan. When speaking to The Sherlock Holmes Society of London and discussing the fact that the original Watson was invalided home after serving in the Second Anglo-Afghan War (1878–1880), Gatiss realised that "It is the same war now, I thought. The same unwinnable war".