Whodunit and Howcatchem

There are two types of murder mystery stories - the whodunit and the howcatchem. The whodunit is the more common one - the one where the audience can solve the crime side by side with the detective. The howcatchem is less common - here, the audience knows who did it from the beginning and is watching as the detective sets about gaining evidence and catching the culprit. As a commenter on this video about the TV series “Columbo” (one of the best howcatchems around) said: a whodunit is a puzzle game, a howcatchem is a game of chess.

Both of these mystery stories have a clear formula to follow and both are interesting to write. So let’s have a look at both of them and at a case I already mentioned (before learning the expression ‘howcatchem’) which combines both of them.

 

Let’s start with the more common one, the whodunit.

The first act of the whodunit gives the audience the basics they need to know. It’s where they meet the victim and the suspects, where the setting is described. It’s also where the murder happens. The first act usually ends with the arrival of the detective or, in cases where the detective arrived earlier, with the beginning of the investigation.

The second act is the puzzle game the commenter referred to. Through the eyes of the detective or someone close to the detective, the audience gets to gather information on the case. This is when interviews happen, officially or unofficially, when clues are found, when suspects are dropped as it turns out they don’t have motive, means, or opportunity (the culprit needs all three). The second act ends when the detective knows who did it and, ideally, has proof of that.

In the third and final act, the detective then solves the case officially, either simply by accusing or arresting the culprit or, more classic, through the ‘you might wonder why I’ve gathered you here’ scene. In that one, the detective gathers all suspects and then describes how the murder happened, one by one telling the suspects why they’re no longer under suspicion until only the culprit is left.

There are cases where the culprit can’t be arrested and will never be punished, but at least they have been caught - the rest is usually up to politics and suchlike.

 

Now, let’s look at the less common one, the howcatchem.

The first act of the howcatchem often starts with the murder itself. At any rate, it begins with the murder preparations. In most cases, the reason for the murder is established early as well, either before or during the act of murder. Again, the first act ends with the arrival of the detective or, in cases in which they were already present, with the beginning of the investigation.

The second act is what differs most from the whodunit. In the howcatchem, the detective either knows or suspects early on who the culprit is, but they need proof (most howcatchem have a professional detective). Therefore, the second act is the aforementioned game of chess. The detective investigates the culprit, trying to prove the alibi wrong, trying to connect the weapon to the culprit, doing all they can to gain evidence against the culprit. The culprit, on the other hand, does their best to stop the detective, laying out red herrings, going to the detective’s superior, buying false witnesses etc. Each tries to outwit the other one. The second act ends when the detective gains the final proof or the culprit manages to deflect suspicion for good.

The third act often includes a trap set for the culprit (if the detective wins) or shows the culprit triumph as they can walk away unhindered, because the detective can’t prove their deed or because they’re untouchable now.

It’s more common in the howcatchem for the culprit to get away (if they are sympathetic and had a good reason for the deed) than in the whodunit. Yet, usually the culprit is tricked into admitting to their deed or otherwise caught and then arrested.

 

Now for the case in between, the movie “Knives Out”.

“Knives Out” starts as a classic whodunit, setting the scene, presenting the victim and the suspects, creating a reason for the murder (as the victim wishes to change his last will to exclude the family). As the murder is happening, the story changes to a howcatchem in which we sympathise with the culprit (the nurse who accidentally injected the wrong dose of a drug the victim needs). As a matter of fact, even the victim sympathises with her - he comes up with a complicated plan to make it look like he was still alive when she left.

As the detective arrives and the second act begins, we are in definite howcatchem territory and see the nurse do all she can to erase the last evidence and keep ahead of the detective. This is when she has unexpected help from one of the victim’s grandsons. It’s also when we learn that the murder happened too late - the victim had already changed his last will and left everything to the nurse. The howcatchem swings back to the whodunit when the nurse acts differently than the actual culprit expects. When she find another employee who supposedly tried to blackmail her poisoned, she doesn’t run away, but calls the ambulance and the police. She’d rather be caught than let someone suffer and die. This is when we learn the detective knew she was there when the victim died - he noted blood on her shoe the first time they met. Yet, we also learn that she had nothing to do with the victim’s poisoning - she gave the right doses after the bottles had been knocked off the table earlier, she only thought she’d done it wrong because of wrong labels on the bottles. She is not the one who planned to kill the victim (who committed suicide rather than suffer the slow death through the drug overdose).

For the third act, the movie swings back to the classic whodunit. Who did exchange the labels, setting up a murder looking like an accident? The grandson did, then ‘helped’ the nurse to get her caught. He also hired the detective to then absolve him and pin it on the nurse and thought that he was still in for money, which he wasn’t. In the third act, the detective and the nurse manage to trick him into admitting it - since the victim committed suicide, he can’t be sentenced for the death. Yet, the employee who blackmailed him originally and whom he poisoned has died, despite the doctors’ best work, so he will go to jail for her death.

The movie is very interesting to watch because of the switches (and I’m absolutely up for a sequel), but this format would probably not work very often. As usually, the formulas work better when they’re pure and need to be fused carefully.

 

Now you know about the whodunit and the howcatchem and can use them, if you wish to. Both types of murder mysteries have their good and bad sides and both can be very entertaining. Learn from “Knives Out” as well - and not just when it’s about mystery stories. Sometimes, formulas can be merged successfully. It’s not something to do lightly, but it is possible.