What makes a Mystery Story a Mystery Story?

This is a companion piece to last week’s blog post about Agatha Christie. And, in a way, to the piece three weeks ago about how I miss the good, old-fashioned mystery stories. I fell in love with mystery stories early in life, sneaking into the adult section of my local library to check out Agatha Christie and Arthur Conan Doyle stories. Luckily, the librarian judged me adult enough to read them and never made a fuss about it - bless her soul.

It is easy to equate mystery story with crime story, because all crime stories are mystery stories. Not all mystery stories are crime stories, though. There’s a very good YouTube video about how the Harry Potter stories are mysteries. Yet, what I am mostly writing about here are crime stories and what makes them different from thrillers. Because there are definite differences there.

“A murder is committed for gain, for fear, or for love.” I already quoted this from the Agatha Christie novel “Hallowe’en Party” as a preface to my last blog post. I did so, because these are the three motives which play into a regular murder mystery - as opposed to the thriller, where things are rarely that personal and clear.

In a murder mystery, just as in most real-life murder cases, most murders are happening because the murderer stands to gain something from the victim’s death. Most of the time, it’s money in some form, often as an inheritance, sometimes it’s also no longer having to pay a debt or gaining money directly during the murder by taking it off the victim or out of the victim’s home.

Another reason to kill is fear - usually the fear of being found out, but also the fear of an abusive relative or superior. At some point, the murderer doesn’t see another way out than to kill the person who threatens them in a way - their freedom, their health, or their life.

Finally, there is what Poirot dubs love in the novel, but I would rather call it emotions, strong emotions. Love, hate, wrath, they all can lead to a final solution. People kill as easily (or even more easily) what they love than what they hate. A crime of passion is usually committed on someone the murderer knows very closely or has another close connection to (even if it’s one-sided).

Everything else, the complicated psychology, the horrible childhood that leads to the murder of total strangers, is for thrillers, where more than just one life is at stake, where the perpetrator has a higher goal than just the removal of one or two people. Sometimes a regular murder looks like it serves a higher goal, sometimes a murder that serves a higher goal looks like a regular one, but in most cases, the murder mystery has murders with a personal motive and no high-flying plans. They also usually have a much lower body-count, making do with one, two, or three murders instead of ten, twenty, or thirty.

One important thing about a mystery story, especially if it’s a murder mystery story, is that it has to be fair. That means the author has to sprinkle in information which will allow for the reader to solve the mystery as well. Nobody says it has to be easy or obvious. Quite often, the important clue is put in while emphasis is put on something which will turn out to be a red herring (are they at least tasty?). The audience needs to get the same information as the detective - whether they do as well with it is another question, of course.

In this aspect, “Murder by Death” is a comedy, but not a murder mystery, because there’s no solution and no way the audience can guess the culprit ahead of or at the same time as the detectives (all six of them fail, which is a major plot point of the story). “Clue,” on the other hand, is both a great comedy and a murder mystery which makes all three endings (a gimmick created for the release, the modern DVD/TV version has all three endings) work and look probable from what we’ve seen before.

It’s easiest to write a murder mystery or any kind of mystery story, if you know the solution to the mystery in advance. J.K. Rowling, of course, knew whether or not Harry would in the end defeat the villain of each book and Voldemort himself. The author of a murder mystery knows who did the deed and how it all happened. Answer the seven questions for yourself and you can construct the mystery story, put in the false leads, and create a very enjoyable book - like Agatha Christie did again and again.

The seven questions can be summarized thus: know why who does what to whom when and where and how. This gives you the motive (why), culprit (who), crime (what), victim (whom), time of the crime (when), scene of the crime (where), and method of the crime (how). Once you know all seven, you can get to work and write your mystery story. In a murder mystery, of course, you will always have a murder or several (and you need to resolve the seven questions for every murder, but some answers, like method or motive, can be the same). For a murder mystery, unlike the thriller, the motive should be something personal (see gain, fear, and love).

There are many ways to play around with those seven questions. The identity of the victim can be tampered with (“The Body in the Library” does that). The time of death can be cheated (“Evil under the Sun” is based on that). The expectations for the murderer can be off (‘all did it’ in “Murder on the Orient Express” and one ending of “Clue” does that). The method can be very complex and hard to put together (as with several murders in “The Greene Murder Case”). It’s important to give the reader all information, but not to make it easy for them to identify what is important and what is not. Hiding a clue in plain sight is an often-used technique. Giving the reader a lot of information at once and putting more importance on a red herring is also common. Building up an obvious suspect, but then making clear they can’t have done it (whether that’s true or not) also happens a lot.

A mystery story needs to have a mystery. It also needs to give the reader the chance to solve that mystery, so no hiding clues or introducing surprise culprits. The mystery must also be engaging - which is pretty much guaranteed with a murder mystery. Mind your seven questions as well and you can write an enjoyable mystery every time.