Major spoilers for Glass Onion, Knives Out, and several Agatha Christie novels.
With Netflix’s Glass Onion, Rian Johnson has produced another highly enjoyable detective story. Daniel Craig’s Benoit Blanc has the perfect Poirot-inspired blend of likeability, slight ridiculousness, and believably extreme intelligence to anchor this type of tale. The mystery itself is intriguing with well-drawn characters and the same lightness of touch combined with subtle social commentary, and it has one of movie history’s more fun red herring characters just wandering around in the background throughout.
However, if we approach Glass Onion as first and foremost a whodunnit, we cannot deny that its mid-film twist breaks the “rules” of a “Fair Play” whodunnit and tricks the audience in a way that most of the best loved examples of the genre do not.
The rules for a “Fair Play” whodunnit were codified by mystery writer Ronald Knox in 1928, and are as follows:
1. The criminal must be introduced early on, and must not be a character whose thoughts the reader has followed.– Ronald Knox, 1928
2. No supernatural agencies.
3. No more than one secret room or passage, and these should only be found in appropriate buildings.
4. No undiscovered poisons, or appliances which need a long scientific explanation at the end.
5. No racist caricatures.*
6. The detective must not be helped by an accident or unaccountable intuition.
7. The detective must not commit the crime.
8. The detective must not find any clues which are not immediately revealed to the reader.
9. ‘The Watson’, i.e. the detective’s friend who is often the main point of view character, must be of slightly lower intelligence than the average reader, and must not conceal any thoughts which go through his mind.
10. Twins and doubles must not be introduced unless the reader has been prepared for them.
Most of these rules can also be applied to a film or TV show. Although viewers do not usually follow anyone’s thoughts in a film or television series, they do usually follow the point of view of a particular character or small number of characters. In Knives Out, for example, the point of view character is Marta. Although the structure looks at first like a Reverse Whodunnit in the style of Columbo, by the climax it actually turns out to be a Fair Play whodunnit, with a minor exception relating to Rule 9 (Marta, who functions as the Watson, is very intelligent; Rule 1 is followed as the villain is mentioned early on).
The point of the “rules” is that the whodunnit is intended to be a puzzle. The reader does not really want to be able to solve the puzzle, as they will generally enjoy being shocked or surprised by the solution, but they want to believe that it is, in theory, possible to solve the puzzle themselves. That is why one of the key rules is that the reader or viewer has access to all the same information as the detective at all times.
Glass Onion does not follow the rules of Fair Play, as it comprehensively breaks Rules 8, 9, and 10 (and flirts with breaking Rule 4). For the first half of the film, the detective has enormous amounts of knowledge the viewer does not, including knowledge of the actual murder that is being investigated, which the viewer is completely ignorant of until the midpoint twist. The audience does not even realize who the Watson is until then, and the plot is suddenly revealed to revolve around a twin the audience had no idea existed until that midpoint reveal.
For an audience conditioned to expect an Agatha Christie-inspired story, this may be mildly irritating. And this film has certainly taken a lot of inspiration from Christie and from some of the films based on her works, even more than the first Knives Out. The title card appearing over dark water in Glass Onion evokes the 1978 film of Christie’s Death on the Nile starring Peter Ustinov, and the following scene showing a group of rich, glamorous people gathering to take a boat to a private island is reminiscent of its follow-up, 1982’s Evil under the Sun. The music as the camera pans across gorgeous Greek beach resorts also cleverly evokes the scores for both the 1978 film and Kenneth Branagh’s 2022 adaptation of the same novel.
The plot of Glass Onion is full of tropes and tricks that appear in Christie’s books; an exotic location, a dead blackmailer, at least two murders and an attempted third, the murderer pretending to be the intended victim, characters posing as their own siblings, an announcement that a murder will take place, an eclectic group of people invited to a private island, and the detective laying a trap for the villain. One of the biggest influences is Christie’s Peril at End House, which features a fancy holiday location, people impersonating their own close relatives, the detective tricking everyone and surprising them all with a dramatic reveal, and the murderer pretending that they are the intended victim to cover up their murder of someone else.
Christie is known for mostly following the rules of Fair Play in her whodunnit stories, and Peril at End House, despite the similar twists, is a “Fair Play” story. In the ITV dramatization made in 1990, Poirot conceals a significant fact from his Watson, his friend Hastings, that he did not conceal in the novel, but even then it is not a clue as such that he hides from him. It is unlikely that many readers work out the solution to the story, but they do have access to all the same information as Poirot and Hastings throughout.
But there are some Christie novels that break the rules; over the course of 74 novels, 166 short stories, and 16 plays, it is hardly surprising that she sometimes decided to mix things up a little. There are Christie works that break Rule 1 (the part about not following the killer’s thoughts), Rule 2 (though only in some less well-known stories), Rule 7, and Rule 9. Some of these are among her most famous and beloved works—spoilers coming up below!
In one of Christie’s most revered novels, The Murder of Roger Ackroyd, the narrator is the murderer. This clearly breaks Rule 1. Fans have been known to defend it by suggesting that because the narrator never actually lies to the reader but only omits information (like, for example, the bit where he committed the murder), it still counts as a Fair Play story.
A quick look at the rules disproves that though—not only does it break Rule 1 by providing insight into some of the killer’s thoughts, it breaks Rule 9 as well, as the narrator is also The Watson, and by not referring to committing the murder, he conceals some of his thoughts (and actions) from the reader. But we should also point out that The Murder of Roger Ackroyd actually came out in 1926, and thus before Knox established his Rules. And more to the point, the twist works. It is a satisfying read, and although the narrator’s story is incomplete, it does include enough clues that in theory, a reader could perhaps solve the crime themselves, despite some withholding on the part of the Watson. In fact, it’s fair to say that the Rule 1-breaking twist is actually the reason the book is so beloved.
The Murder of Roger Ackroyd is a good example of why sometimes, whodunnits have to break the rules in order to work. Another is Christie’s And Then There Were None, which is so successful that it is the best-selling mystery novel of all time. This story also breaks Rule 1 by providing a brief insight into the murderer’s thoughts. However, this novel simply would not work if it did not break the rule.
The setup is that 10 strangers have been invited to a mysterious island where one of them starts killing off the others, one by one. The opening chapter reveals the thoughts of eight of the 10 victims/suspects in the case as they make their way to the island, including the murderer. To leave the murderer out would be to give away their identity. (The two suspects whose thoughts are not revealed are the two servants, presumably because they have been hired for work rather than receiving a mysterious invitation).
In the case of Glass Onion, the reason for the rule-breaking is that only the second half of the movie is actually a whodunnit. Halfway through the film, an attempt to shoot Janelle Monae’s character to death prompts a rewind of the whole film and the audience are shown the events of the first half with a new perspective. It turns out that Monae’s character is not who we thought she was, and that Blanc is not there to play a game or to investigate possible attempts on Miles Bron’s life. Rather he is there to solve the murder of Andi Brand, and has been hired by Monae’s character, who is actually Andi’s identical twin sister Helen Brand.
Once the viewer is let in on what is actually happening in Glass Onion, the rest of the film follows the rules of a Fair Play mystery. From the moment we catch up to Blanc looking down at Helen with a single tear on his face (caused by some chili and not her death after all), the viewer has been presented with all the clues to the mystery, as well as key information on the characters’ backgrounds and motivations, and the rest of the film proceeds as a Fair Play whodunnit.
The first half of the film is the part that breaks the rules, and that is because the first half of the film is not actually a whodunnit, it is a suspense thriller. The “rules” of that genre are rather more flexible. The focus is on action and threat, and the reader or audience expect to be shocked and surprised by twists they did not—and could not—see coming.
Rian Johnson is a big fan of the films of Alfred Hitchcock, as well as the novels of Agatha Christie, and indeed Christie herself wrote several thrillers in addition to her better known whodunnits, which are not constructed as “Fair Play” puzzles. Johnson already blended the two genres to great effect in the first Knives Out movie. Although that film is much closer to a Fair Play whodunnit, the Columbo-inspired middle section takes on the form of a suspense thriller, in which we watch a sympathetic character deal with unexpected trouble. Johnson talked to Collider about this in detail back in 2019, explaining why Hitchcock hated whodunnits and how he structured the movie to start out as a whodunnit, switch to Hitchcockian suspense for the middle part of the film, and then flip back to a whodunnit at the end.
The first half of Glass Onion, despite all the nods to Christie’s novels and the film adaptations of them, is not actually designed to be a mystery that the viewer can solve. It is, rather, a suspense story with a twist intended to surprise the viewer and encourage them to watch the film multiple times so they can view each scene with a fresh perspective. It rewards re-watching the film because once you know what you are looking for, you can see that the woman who smashes the box sent to Andi has her hair covered to hide her true identity, you realize that Blanc’s partner tells him someone is here to see him “with a box” rather than a box being delivered by courier, and you can understand the significance of Miles’ reaction to “Andi” appearing on the island, and her muttering “this rich people shit is weird” to Blanc takes on new meaning as well.
But although these reward a re-watcher with little details relating to the reveal, they are not “clues” to a puzzle the viewer can solve. There is no way the viewer could guess that “Andi” is really Andi’s twin sister Helen, because no one mentions Andi having a sister, never mind an identical twin sister. (Compare this with just about any Agatha Christie whodunnit involving siblings or cousins posing as each other—in Christie’s stories the existence of the sibling or cousin at the very least will have been revealed early on). That is exactly why Rule 10 is “no twins.” Unless the viewer is taking wild stabs in the dark about the plot, which has no basis in anything that’s happened, they cannot possibly guess that this is what’s going on. Nor does the audience get any clues that Andi is dead. They are as clueless on that point as the other suspects, even though both the detective and the Watson are fully aware of it.
This is not a problem at all if the viewer wants to enjoy a suspense thriller with a twist that prompts them to rewatch the film and see each scene in a new light. Glass Onion does that perfectly. But if the viewer wants a mystery story that they have a chance of solving themselves—well, they will get there in the end, but they’ll be well into the climax of the movie before they reach that point. Glass Onion is a great, fun movie, but for mystery fans, it can also be just a little bit frustrating.
Ultimately, the “rules” aren’t about restricting the creativity of writers or their ability to shock their readers/audience. They are about producing a mystery that is satisfying for the reader or viewer. The idea behind the rules of “fair play” is that the reader or viewer wants to theoretically be able to solve the mystery, and they want to be able to solve the clues—or, if they are surprised by the reveal, to see how they could have seen it coming. So if you want a classic whodunnit, then you might prefer the film to follow the “rules” or at least to confine itself to breaking only one, and only in a small way. That will create a more satisfying experience because the solution will tie together clues you have already seen.
Of course the beauty of Glass Onion is that both types of audiences get to enjoy their preference—just remember that the first half is the suspense thriller, and it is the second half that is the whodunnit!
*Knox’s rule was specifically “no Chinaman,” but this is what he meant—he was referring to a racist caricature popular at the time.