Crime fiction was a creation of the modern world and its suddenly growing cities, when in both reality and fiction specialists emerged to identify criminals and protect the anxious, isolated citizens. At first they tended to be lawyers, but then detectives, both amateurs and police, came to play a central role.

The development of crime fiction has its own mysteries. The book explores theme-focused aspects of its complex history through the nineteenth century. The first two chapters show how America and France generated new forms of crime fiction, often influencing each other. The next chapter reveals social variations among the early investigators, and then gender is the focus for a discussion of the roles played by women as authors, and even detectives.

Chapter 5 studies how major English writers like Gaskell, Dickens, Collins and Braddon were influenced by and contributed to crime fiction. The book concludes by analyzing how and why Hume's The Mystery of a Hansom Cab became a best-seller in 1887-8; finally it exposes the imperial features, some of them already post-colonial, which helped to make the Sherlock Holmes stories seem dynamically up-to-date.