Decoding Agatha Christie

How to Spot the Killer in One of Her Novels

Yes, yes, I know–for many of you, Agatha Chrisitie is the antithesis of everything private eye, and belongs on this site about as much as tofu recipes or lectures on the breeding habits of dung beetles.

But let’s give credit where credit is due–Christie is, of course, the undisputed Queen of Crime, arguably the most widely published novelist of all time. She is the author of over eighty crime novels and short story collections, 19 plays, and six novels written under the name Mary Westmacott, but is best known for creating two of the world’s most popular sleuths, amateur sleuth Miss Marple and finnicky Belgian private investigator Hercule Poirot. She also created one of the very first husband-and-wife private eye teams, Tommy and “Tuppence” Beresford.

And no, I’m not going to argue that any of her books are particularly hard-boiled. At best, most of them are slowly simmered. But she certainly knew evil when she spotted it, and despite the often outlandish machinations of her plots, at the core of almost all of Christie’s murders was something genuinely and inarguably evil–something her more hard-boiled rivals should remember. It’s easy enough to make a gangster, an out-of-his-head junkie or a serial killer into a villain, but to credibly and regularly–book in and book out–create a villain out of an unlikely suspect takes some kind of awesome skill.

On September 15, 2020, on the occasion of what would have been her 130 birthday, The Grand Theatre of Blackpool, England released the following infographic, “Decoding Agatha Christie,” a helpful guide for both readers and would-be crime writers that, as another famous crimewriter once put it, “lifts the lid and lets you get a good look at the works.” 


  • With work translated into 103 languages and famous characters like Hercule Poirot and Miss Marple, Agatha Christie is an acclaimed writer. Using Simple, middle-range language that is repeated throughout her work, Agatha Christie’s detective novels have seen many adaptations. From murder and mystery, she takes us through scintillating whodunnits in which we can’t help but try to find the murderer. But could you spot the killer in one of her novels?

The Plotting Method

  • Finding the murder, killer, and purpose
  • The suspects and their intents
  • The potential clues and red herrings

The Key Events

  • A body is found early on
  • A few suspects are presented
  • The detective arrives
  • Red herrings to throw you off
  • The killer is found

The Plot Devices

  • The Disguise
  • The Discredited Witness
  • The Least Likely Suspect
  • Intuition
  • The Locked Room
  • Servants and Employees
  • The Big Reveal


  • Poirot as Detective
  • If the victim dies by stabbing, you’ll find the killer mentioned more in the beginning
  • Miss Marple as Detective
  • If the motive is money or an affair, you’ll find the killer mentioned more in the ending

The Victim

  • Typically connected to the killer by blood or marriage
  • Death by strangulation or stabbing suggests a killer doctor

The Clues

  • Meet the killer in the first 20% of the book
  • Key Clue is unveiled around halfway point
  • Clue of little relevance is often ‘interesting’
  • Clue of high relevance is often described simply
  • Male Killer
  • Victim is strangled to death
  • Higher levels of positive or neutral sentiment
  • Comeuppance through reasoning and logic
  • Nautical or air mode of transportation
  • Female Killer
  • 75% chance when the novel is set in a country home
  • Higher negative sentiment
  • Discovery of a domestic item
  • Land mode of transportation, like train or car


Respectfully submitted by The Blackpool Grand Theatre. To find out more about their fantastic plays and theatre productions, check out their shows here.

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