Foucault's Pendulum by Umberto Eco (1988)

This is a brilliant book, once you understand it. I must confess, I found it heavy reading, but then I read it again, and then again, and slowly realized what a brilliant book it is. Foucault's Pendulum is a book that delves into conspiracy theories, but the concept in the book is more about detailing how weird conspiracy theories can be, how they can drive people totally delusional, and so on. As a side note, the book is nothing like the much more popular 'The Da Vinci Code' by Dan Brown (that dealt with real life conspiracy theories while "Foucault' Pendulum" is more about how conspiracy theories are bunkum, but have enough adherents to provoke strange reactions in people, especially in people who have bought into such theories. Foucault's Pendulum by itself does not promote a conspiracy theory, but integrates many prevalent theories related to the Knight Templars, Freemasons, The Elders of Zion, The Cabalists, The Jesuits, The Bavarian Illuminati, and many others, and adds one more fictional cult of its own - a fictional secret society called the Tres (Templi Resurgentes Equites Synarchici, Latin for the nonsensical "Synarchic Knights of Templar Rebirth").



The name of the book is fascinating in itself, talking about the famous experiment by the French physicist Léon Foucault, in the year 1851, in the Meridian Room of the Paris Observatory. This experiment involved hanging a tall pendulum free to oscillate in any vertical plane; over a period of time, the paths taken by the pendulum will demonstrate the rotation of the earth (Wikipedia); this device forms an integral part of 'The Plan' described in the book.
The book is itself about these 3 characters, Belbo, Diotallevi and Casaubon (the narrator, describing the events in flashback), who get interested in conspiracy theories, the occult and decide to prepare their own theory called 'The Plan'. Their personal histories are described in detail, including their earlier review of a book on the 'Knights Templar' which describes how the holy warriors did not totally die out when they were suppressed by the French Emperor and the Pope, but instead the remnants of the order went underground, established cells throughout the world in order to eventually take over the world and avenge their destruction. Their are other experiences of interaction with occult ideas and other conspiracy theories.
Eventually, the 3 develop their own conspiracy theory that includes many elements, and weaves together an intricate web, taking the help of the personal computer of Belbo (called 'Abulafia'). Eventually, they start attracting the attention of a secret brotherhood that imagines itself to be secret society described in this plan, and which wants to capture these 3 authors for learning more about what they know, and capture Belbo in order to force him to reveal more. This eventually leads to his death at the hands of the gang when he is unable to provide them more information.
Casaubon escapes, and is left thinking about what they have created, and when he will be eventually captured by this society. He is clear that he will not let them believe that 'The Plan' is real.

The Murder of Roger Ackroyd by Agatha Christie (1926)

The concept of a narrator of a detective story has been prevalent for a long time. The most famous probably being the character of Dr. Watson from Sherlock Holmes who was the perfect foil to Sherlock Holmes. There are some expectations from the narrator of a good detective novel - the narrator can bring their own quirks to the story, but they are expected to layout the story in the way that it actually happened. You don't really expect the narrator to have a significant presence in the story; this was the concept that was used before the advent of this novel.
The Murder of Roger Ackroyd turned this whole concept upside down. Here was a narrator who was going along normally like most narrators, and then at the end, there is a huge element of surprise. Hercule Poirot points out that the murder was committed by the character of the narrator, and the narrator admits this as the last element of the story before committing surprise.



This twist in the novel was very controversial. After all, the concept of a good detective novel was that you provide the same clues to your reader as available to the detective, and if you hide a major element in the story (such as the narrator having done the killing), then it would almost seem like a break to that concept. Fortunately for this novel and Agatha Christie, except for some critics and reviewers, everybody else accepted this twist easily enough. In fact, many consider this to be among her best works.
The story is about the double murder in the small town of King's Abbott in England. The murder of Mrs. Ferrars happens first, and then the murder of Roger Ackroyd clears the lingering doubt about Mrs. Ferrars death was a murder. There are a variety of suspects with their different motives, with suspicion falling strongly on Ralph, the stepson of Roger Ackroyd backed by many pieces of evidence. And then Poirot steps in, having newly arrived there. What does Poirot do to absolve Ralph of the crime ? As usual, Agatha Christie has spun a great tale.

Appointment with Death by Agatha Christie (1938)

Agatha Christie created 2 fabulous characters - Hercule Poirot, and Miss Marple; each of them were brilliant at connecting clues, tying them in with human emotions and solving crimes that would baffle other people; in that respect, they were similar to Sherlock Holmes (created by Sir Arthur Conan Doyle). Hercule Poirot was made as a lovable, and yet highly vain character. He knows that he is smart, he can solve cases that no one else can, and he is very vain about his moustache. He is also a perfect gentleman in terms of manners, although with a high ego, he can get easily offended. All these characteristics pale in front of the indisputable fact that he can use clues to evolve a story, change his thinking if the clues don't match, and explore all possible alternatives even if they seem extremely unlikely.



This particular novel, 'An Appointment with death' was released after many other Hercule Poirot stories had been published, so the standard for Hercule Poirot in terms of character and success was already set. Here was a guy who read the same clues as the reader, and others in the story, and yet was able to solve the crime (in many cases, the actual murdered was a surprise to most people - read 'Murder on the Orient Express' as another great book with the same subject).
The novel deals with a family under great stress, the matriarch of the family is a tyrant of the highest degree, controlling the family (interactions, emotions, experiences, she controlled everything). This stifling was causing immense harm to the family members (including possibly breaking up the marriage of her son), and then, while on a trip to the Middle East, she is murdered. There is not much time to solve the crime, and since Hercule Poirot was at the same location, his services were requested. He needs to figure out the various movements, marshal the clues, and see which of the oppressed family members committed the crime.
The initial part of the story where the family is getting discussed between 2 outsiders, Sarah King and Dr. Gerard, is fascinating as you get to understand the family dynamics in fair detail. This is setting the ground to claim that most people in the family also had a reason to kill her, and then Poirot had heard something earlier that seemed like her children were plotting to kill her. In the 24 hours in which he was involved in the case, he works out that the family members had indeed found her dead, but suspected the other and hence tried to save them.
The name of the murderer, when finally revealed, is a major surprise, one which most readers would not have predicted.