Sir Isaac Newton’s work in the fields of physics and mathematics moved our knowledge of the world forward by leaps and bounds. It’s still the basis for our understanding of how the physical world works. And if you think about it, we can also see Newton’s laws at work in the world of crime fiction. Consider, for instance, Newton’s first law of motion, which states that a body at rest (or in motion) remains at rest (or in motion) unless acted upon by an equal outside force. Most of us think of this as inertia. People are often that way as well, and a look at crime fiction shows how that can work in the genre.

In Agatha Christie’s The Murder of Roger Ackroyd, Hercule Poirot retires (or so he thinks) to the small village of Kings Abbot. He is soon drawn into a murder case, though, when he is asked to investigate the killing of retired manufacturing tycoon Roger Ackroyd. It’s not an easy case, but Poirot works out who the murderer is. At one point, towards the end of the novel, he’s describing the likely personality of the murderer:

“Let us take a man—a very ordinary man. A man with no idea of murder in his heart. There is in him somewhere a strain of weakness — deep down. It has so far never been called into play. Perhaps it never will be — and if so he will go to his grave honored and respected by everyone. But let us suppose that something occurs.”

In this case, inertia probably would have kept the killer from committing murder, except that a certain event propelled that person to plan and carry out the crime.

As James M. Cain’s Double Indemnity begins, insurance representative Walter Huff is in the Hollywood Hills area of Los Angeles. He decides to stop by the home of one of his clients, H.R. Nirdlinger, to see if he can get an agreement for a policy renewal. Huff isn’t a particularly adventurous or dangerous person. He’s quite ordinary in a lot of ways and probably would have kept on in the same vein. Instead, he meets Nirdlinger’s wife, Phyllis. He’s immediately attracted to her, and she does nothing to discourage him. By the time they finish their first conversation, he’s smitten, and it’s not long before they’re having an affair. Huff becomes so besotted with Phyllis that he falls in with her plan to murder her husband for his insurance money. In fact, Huff writes the double indemnity policy she wants. The murder goes as planned, but then, things start to spin out of control, and it all ends in tragedy. In this case, you might say that Huff’s affair with Phyllis Nirdlinger was the force that impelled him to break out of the ordinary insurance-salesman life he’d had.

In Pascal Garnier’s How’s the Pain, twenty-one-year-old Bernanrd Ferrand is sitting on a park bench. He’s a bit aimless and at the same time, he’s affected by a sort of inertia, with no specific direction to his life. Then, he meets Simon Marechall, who says he’s a pest exterminator. Marechall discovers that Ferrand has a driver license, and that’s exactly what he’s looking for. It turns out that Marechall is a hired killer who wants someone to drive him to the south of France for one last job before he retires. Ferrand agrees to be Marechall’s chauffeur, but he doesn’t know at first what sort of trip this will be. As the story goes on, he finds out, and things soon go very much awry. It’s possible that Ferrand would have stayed in his ordinary life without the impetus from Marechall.

Karin Alvtegen’s Betrayal is the story of Eva Wirenström-Berg and her husband Henrik. They’ve been married for fifteen years, and have a six-year-old son, Axel. In other words, they’re living exactly the ‘white picket fence’ life that Eva has always wanted. Then, Eva discovers that Henrik has been unfaithful. As you can imagine, she’s devastated, and she’s determined to find out who the other woman is. When she does, she sets in motion a plan that isn’t going to have the results she wanted. In the meantime, we also meet Jonas Hansson, who has his own burdens to bear and has suffered his own tragedy. When his life intersects with Eva’s life, things end up spinning out of control. It’s quite possible that Eva would have stayed in her ordinary middle-class life without much change if she hadn’t found out about her husband’s infidelity. That’s arguably the force that impelled her to act.

Graeme Macrae Burnet’s The Accident on the A35 begins with the death of an attorney named Bertrand Barthelme. At first, it looks as though it was just a terrible accident – a case of a man who lost control of his car and drove it into a tree. But, as a routine part of the investigation, Georges Gorski, local chief of police, visits the family. From Barthelme’s widow Lucette, Gorski learns that the victim had dinner plans at a restaurant that wasn’t anywhere near where his body was found. In fact, there would have been no reason for him to be on that road that night. With that in mind, Gorski begins a more in-depth investigation. In the meantime, Barthelme’s son Raymond decides to look for answers on his own. He’s never been close to his father, and now he wants to know who his father was as a person, and how he came to be where he was when he died. The death of his father jolts Raymond out of his ‘samey’ sort of life and spurs him to go on his own sort of quest for answers.

See what I mean? Inertia arguably impacts people, just as it does the physical world. Physics is everywhere. And you thought Newton had nothing to do with crime fiction…

*NOTE: The title of this post is the title of a song by Spectator Bird.