How to Write a Great Whodunit Screenplay

Screenwriters Network, February 23, 2021

When it comes to writing a whodunit movie, there’s so many elements you need to have to make your film stand out.

Audiences don’t want to see a film they’ve seen thousands of times before! If you’ve always wanted to write a great whodunit film, here are some tips on how to write a memorable one.

Focus on the story

Like in any genre, you have to focus on the story first. Whodunit films aren’t just about someone being murdered, there’s so much more to the story if you want to make it more dynamic!

Even before the victim is murdered in the film, each main character needs to have a backstory, so the audience has an idea of who they are.

For example, in the recent hit movie Knives Out, although we see the murder early on in the film, detective Benoit Blanc investigates each of the family members and we get a sense of each family member’s relationship with the murdered victim.

Make your story unique

In the scene in Knives Out where Blanc interrogates Marta, Harlan’s personal nurse, is a good example. We quickly learn that whenever she lies, she vomits. Blanc first asks her if Richard was having an affair.

After a brief flashback shows Harlan showing photo evidence of Richard having an affair, Marta tells Blanc, “No” then vomits a few seconds later. So, throughout the film we now know whenever Marta vomits, she’s lying.

Keep the audience guessing

When you’re writing a whodunit film, you must always leave the audience guessing, but don’t make the film too confusing. It’s important to note that every character must look like the murderer.

In fact, you can drop a hint or two of who the murderer could be, but don’t make it too obvious or else the audience could lose interest.

Think of the audience as a detective and have them play along with the protagonist in the film as they go about investigating the murder.

Perhaps one way you can do this is make one of the characters look like they’re the murderer but suddenly kill them off. That way the audience is took by surprise and has to reevaluate the clues from earlier in the film.

The character has to have a motive!

What motivated them to cause the murder? It isn’t normal for murderers to commit a crime with no reason whatsoever. Perhaps they wanted revenge on someone who wronged them.

Maybe the murderer was jealous of someone and wanted them out of the way so they could get what they want. The possibilities are endless, just make sure that it’s clear to the story you’re trying to tell.

For example, in the horror slasher film Scream, Randy explains to Stu that all the police have to do is follow horror movie formulas to find out who the murderer is, which is ironic because little does he know, he’s talking to a horror fanatic and is a little bit crazy.

However, in the end of the film, we learn both Stu and Billy were the murderers after all, but Billy was the one who had a motive. Billy committed the murders due to his parents break up, while Stu on the other hand is just plain crazy and fell into peer pressure.

If you’re unfamiliar with whodunit movies, but want to give it a try, it’s usually best to first watch a few different whodunit movies before you start writing one yourself.

Not every whodunit is going to be the same and although there are similar tropes, you still have to make it unique and original.

So, before you start writing your whodunit script, it’s usually best to take a look at some films of the same genre and make it your own. Movies such as Knives Out and Scream fall under the whodunit genre, but they’re a bit different from each other and unique in their own way.

All of those films tell a story, they keep the audience guessing, and the murderer has a motive.



Contributor: David Schwartz

About the author: David Schwartz is a freelance script consultant and screenwriter. He graduated college in 2018 and has wrote a variety of short films and features. Since graduating with an AA in TV/Film Production, he has gone on to working on his scripts and sending his scripts to screenwriting contests and getting feedback from professionals in the industry. If you would like some feedback on a script, please check out his website:



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