Arthur Conan Doyle’s medical and writing careers intertwined and his work has a history of being read in the light of his medical expertise. He wrote at a time when the professionalisation and specialisation of medicine had resulted in an increasing distance between the profession and the public, yet general practitioners relied financially on maintaining good relationships with their patients and popular medical journalism proliferated. A variety of contrasting voices often disseminated narratives of medical science. These conflicting developments raised questions of authority and expertise in relation to the construction of medicine in the popular imagination: how is knowledge constructed? Who should disseminate it? How and by whom is authority conferred? How can the general population judge experts in medical science? These are questions explored more widely in Conan Doyle’s writing as he examines the relationship between expertise and authority. In the early 1890s, Conan Doyle wrote for the popular, mass-market periodicalThe Idler: An Illustrated Magazine. His contributions to it address these questions of authority and expertise for a lay audience. First establishing the medical context of doctor/patient relationships in which these questions arose, this article undertakes a close reading of these mostly rarely studied single-issue stories and articles as a means of ascertaining how Conan Doyle and his illustrators identified the relationship between competing narratives, expertise and authority. It argues that rather than maintaining a distance between public and professional, Conan Doyle’s illustrated work demonstrates to his readers that there are ways to successfully navigate the appearance of authority and recognise expertise as they confront entangled representations of advances in medical science.