When I would read Miss Marple stories by Agatha Christie, I would almost never be able to guess the killer. I would introduce all sorts of complexities into my guesses: the most suspicious person is obviously not the killer. It is probably the least suspicious, or the most medium-suspicious (median-suspicious?). But regardless of anything that I did, I got it wrong 100% of the time. A few years later, I came to know how Agatha Christie decided who was the killer in her stories: she would write 90% of the story, and make a lot of people read it. She would then poll everyone on who they thought the killer was, and just choose the person who got the least number of votes. This taught me how constrained I was even in my imagination, and how humans primarily think in the same manner.
I have also enjoyed watching Hindi whodunnits like “36 China Town“, “Raat Akeli Hai” and “Aranyak“. Although these three vary wildly in quality, I was surprised when I came to know who was the killer in all of them. It’s not just that I didn’t get the killer right; the actual killers were not even on my radar. The explanation is simple: the killers in all three appeared to be devoid of agency. The killers in 36 China Town were servants, who are expected to servile and not have a decision-making role (unless they are actively seen by the audience to be planning something, which they were not in this case). The killer in Raat Akeli Hai was a teenage girl who was initially shown as completely controlled by her mother, and hence was perhaps subconsciously eliminated by the audience as the possible culprit. The killer in Aranyak was again a servant who was initially shown to be obsequious to the point of slavery. Perhaps we subconsciously expect a killer to have agency/power, and anyone who is not initially shown to have any is assumed to be innocent.
I am currently watching Season 9 of Father Brown, which is also by and large a whodunnit. However, it seems to employ a rather different pattern. Most detective stories are based around misleading the audience as to the actual identity of the killer, and then shocking them with the big reveal at the end. And to be sure, Father Brown has a lot of that too. However, in some of the better episodes, the most obvious guess does turn out to be right; the person with the most genuine grievance or anger does turn out to be the killer. However, the motive is slowly revealed to be more intricate and nuanced than the audience expects, adding a layer of depth to the story. For instance, in the episode I watched today, a man is shot at a party, and everyone suspects a stranger at the party who had argued with the man. And surprise surprise, that stranger had indeed been the culprit. However, what the audience didn’t expect was that the stranger had had a homosexual relationship with the victim’s son, and the victim had had the stranger imprisoned and chemically castrated, which caused the stranger to seek revenge. I rather enjoyed this episode, despite the somewhat obvious identity of the killer.
This is a trope that Raat Akeli Hai also employs: everyone expects the murder to have happened for wealth or property. However, it is revealed at the end that the murder actually happens because the victim had had forced incestuous relations with his own granddaughter. This added layer of complexity to the plot is what made the movie memorable, as opposed to just making the whodunnit harder to solve.