For instance, in Arthur Conan Doyle’s The Adventure of the Empty House, Sherlock Holmes uses people’s tendency to fall into habits to catch a killer. Holmes is on the trail of the murderer of Sir Ronald Adair. On the surface, there doesn’t seem to be any reason to kill Adair, as he didn’t appear to have enemies, nor did he have a fortune to leave. Holmes figures out who the murderer must be, and has discovered that the killer is also tracking him and watching his Baker Street rooms. So he lays a trap for the murderer. He creates a dummy figure and sits it in the same chair and with the same lighting as he himself is in the habit of using. The dummy is lifelike in silhouette, and Holmes has his landlady Mrs. Hudson move the dummy at specified intervals, so that from the outside, it looks as though Holmes is there, following his usual habits. The killer is tricked into believing his target is at home and tries to kill him. Holmes and Watson, though, have tracked the killer down and Holmes is able to stop his enemy.
There’s an interesting study of people’s habits in Agatha Christie’s Three Act Tragedy (AKA Murder in Three Acts). Hercule Poirot has been invited to a cocktail party at the home of noted actor Sir Charles Cartwright. During the party, one of the guests, beloved clergyman Stephen Babbington, suddenly dies of what turns out to be poison. There seems to be no motive for the murder, as Babbington was well-loved and had neither money nor greedy relations. Poirot works with Cartwright, Mr. Satterthwaite (who was also at the party) and fellow guest Hermione “Egg” Lytton Gore to find out who poisoned Babbington and why. As they investigate, two more deaths occur, and it’s soon clear that all three deaths are related. What’s interesting about all of the murders is that the murderer gets close to the victims by taking advantage of people’s normal habits. In the end, Poirot figures out what the common thread is in the murders and puts the pieces of the puzzle together.
In Christie’s Death in the Clouds (AKA Death in the Air), we see another example of a murderer who takes advantage of people’s habits to commit a crime. In that novel, Poirot is traveling by air from Paris to London. On the same flight is French moneylender Madame Giselle. Towards the end of the flight, Madame Giselle suddenly dies of what seems at first to be heart failure. That makes sense, too, since there was a wasp in the cabin and the victim has a small puncture wound. Soon enough, though, it’s proven that she died of poison. The only possible suspects are the other people who were traveling in the same cabin of the aircraft, but no-one saw any other passenger step close enough to Madame Giselle to poison her. In the end, Poirot figures out that the murderer relied on a habit people have in order to get close enough to kill Madame Giselle.
A killer also takes advantage of a habit in Simon Brett’s What Bloody Man is That?. Down-and-out actor Charles Paris gets a chance at resurrecting his career when he gets a small part in a provincial repertory company’s production of Macbeth. The lead actor in the play is obnoxious Warnock Belvedere, who’s succeeded in making enemies of just about everyone in the company, including Paris. Belvedere’s got a drinking habit, and keeps a secret stash which he makes use of when he has some privacy. One night after rehearsals, his habit and his personality catch up with him when he dies of poisoning after drinking some of his hidden liquor. Paris, who’s been doing plenty of drinking of his own, falls asleep in the theatre and is trapped there overnight. When Belvedere is found dead the next morning, Paris is suspected of the crime. Now, Paris has to sift through the long list of Belvedere’s enemies to find out which one of them was responsible for the killing.
In Luis Alfredo García-Roza’s Alone in the Crowd, we meet Dona Laura Sales Ribeiro, a woman of very, very regular habits. Every month as if on cue, Dona Laureta visits Rio de Janeiro’s Caixa Econômica Federal, where she cashes her pension check at the teller window of Hugo Breno. Then, she goes home. One day, though, instead of going home, Dona Laureta goes to the 12th Precinct and asks to speak to Inspector Espnisosa, whom she’s never met. When she’s told that he’s in a meeting and can’t be disturbed, she agrees to come back later and speak to him then. On her way home from the police precinct, Dona Laureta is waiting with a group of other passengers at a bus stop when she suddenly falls or is pushed under an oncoming bus. When Espinosa finds out about the death, he thinks at first that it was an accident. Then, when he’s told about Dona Laureta’s visit, Espinsoa begins to believe her death might not have been accidental and starts to investigate. He eventually finds the connection between Dona Laureta, a mysterious man who’s been shadowing him, and his own past. In this novel, you could say that Dona Laureta’s regular habits made her especially vulnerable.
Mavis Gillespie’s habits are quite literally the death of her in M.C. Beaton’s Death of Maid. She’s a charwoman with the best reputation in the area. So when Constable Hamish Macbeth wins her cleaning services in a raffle, he ought to be thrilled. Instead, he discovers that she hasn’t done a good job of cleaning at all, despite everyone’s saying what a find maid she is. To make matters worse, she’s stolen a private letter of his. When Macbeth goes to confront her with her slipshod work and the theft of the letter, he finds out that it’s too late; Mavis Gillespie has been murdered. As Macbeth investigates her death, he finds out the reason for her stellar reputation; she had a habit of snooping and of blackmailing people with what she found out about them. That habit of being too curious for her own good got someone frightened enough to kill her.
Christopher Boone, who’s featured in Mark Haddon’s The Curious Incident of the Dog in the Night-Time, is very dependent on his habits. He’s got autism, and although he’s high-functioning, he relies very heavily on carefully structured routines. He also notices others’ habits and routines and is extremely observant. One day, Boone discovers that his neighbour’s dog’s been killed. When he’s found near the dog, he’s accused of being responsible for what happened. In order to clear his name, Boone decides to be a detective just like Sherlock Holmes. To do that, he has to make use of what he knows about everyone’s routine and he has to face his own reliance on structure. It’s an interesting study of how much we depend on the habits we’ve formed.
We all have habits, so it’s no surprise that they come up in crime fiction. I’ve only had space to mention a few examples; there are lots more. Do any come to your mind?
*NOTE: The title of this post is a line from Chicago’s Hard Habit to Break.