A mystery (sometimes called a detective or crime novel) focuses on an individual, usually a detective, who solves a crime, often a murder. Edgar Allen Poe was one of the first to write such stories, and from his first name comes the Edgar Awards, given annually to the best examples of this genre. This genre has several common elements.
Often the crime happens before the novel opens. In The Cuckoo’s Calling by J.K. Rowling (using the pen name of Robert Galbraith), the murder (or is it a suicide?) happens minutes before the opening scene in which the police and medical examiner investigate the corpse. In Agatha Christie’s And Then There Were None, the murders happen as the book progresses, after characters and setting are established in the readers’ minds. Either way, we readers do not usually develop an emotional connection to the victim.
If the crime begins the story, the next chapter introduces the detective, interrupted while living his usual life. Agatha Christie’s Miss Marple might be knitting with a friend, or Raymond Chandler’s Philip Marlow might be drinking in a favorite bar. Elizabeth George’s Thomas Lynley might be heading to his estate for a family gathering.
The detective-protagonist is proactive: looking for clues, meeting with suspects, talking to the police, and facing danger. He often reaches a low point well into the story from which he emerges a better person. Sherlock Holmes is a damaged protagonist—a drug addict. Philip Marlow is an undiagnosed alcoholic and chain smoker. Such character flaws make the detective more realistic.
Sometimes the detective has a side kick. Dr. Watson is Holmes’. Sergeant Barbara Havers is Lynley’s. But many detectives, like Hercule Poirot, work alone.
The antagonist is the killer, but since we don’t know who he/she is, almost all the characters are antagonists whose alibis, means and motives need to be studied. Sometimes a character whom we assume to be innocent turns out to be the killer, making for a clever twist at the end. The antagonist must be cunning, resourceful, and indefatigable—the same characteristics as the detective, so their battle of wits, like Holmes’ and Moriarty’s, seems matched.
Suspense is important to sustain reader interest. So is foreshadowing and surprise. Many times the detective finds himself or herself in danger. Evidence is revealed little by little, asking the reader to infer what each clue might mean. Some true clues are brushed over while red herrings are traced to their dead ends.
Many mysteries put a cast of characters in a closed off situation—on a train or on an island—so we know one of them has to be the murderer. P.D. James used this strategy as did Agatha Christie. Other writers, like Raymond Chandler, don’t close off characters physically, but motive or opportunity limits the likely suspects. Picturing the setting is important, and writers describe in great detail where rooms or items within rooms are located.
The fun of this genre is trying to solve the murder before the detective identifies the murderer. Satisfaction also comes from appreciating the fine mind of the detective as he explains how he (or she) solved the crime.