On June 21, Kingston Hospital Radio Online tweeted an interesting little tidbit about the music used in The A. B. C. Murders that Hugh Fraser retweeted, and so it came to my feed…
For my part, I was both delighted and sort of chagrined that I had never noticed this before. Last night I finally re-watched the episode, and the A-B-C motif positively screams to high heaven. Once heard, it cannot be unheard. I also realized that a full-fledged lay analysis was inevitable at that point, and so I watched through the episode sitting at my piano keyboard to see just what happens with the alphabet (musically) throughout the episode. I won’t go through quite the entire thing here– there are about a hundred key changes and transitions– but I’ll share some of the more interesting highlights. 🙂 ***Plot spoilers ahead***

As a bit of an aside, is it coincidence or not that we see, on two different pieces of Hastings luggage, his initials? I’m not sure we see this in any other episode.
The very first thing we see in the episode, which I love, is the rack of ABC railway guides at the station where Poirot is waiting for Hastings. A familiar cane appears to straighten those that are sticking out a bit. The very blatant A-B-C notes (representing the first three notes of the A minor scale) are the first things heard, and they quickly mingle with the Poirot theme, which has been transposed up a step from G minor to A minor and also contains those first three notes. This may explain why you can watch the episode so many times without realizing you’re hearing A-B-C… it just sounds like the beginning of the Poirot theme transposed (A-B-C-E-A from G-A-Bb-D-G). Clever. 🙂
Throughout the episode– for example, early on when Poirot and Hastings are first discussing the first letter– the A-B-C motif is sometimes paired with Eb-F-Gb to create a series of creepy-sounding diminished fifths. What better way to emphasize the unresolved tension of letters sent from a homicidal maniac? Diminished fifths give that delightful sensation of “something is really sick and wrong here.”
Whenever a new message from A. B. C. appears, the key reverts to A minor, and this also frequently happens when we encounter Cust. (Although he is also an A. B. C. in a manner of speaking, this is a bit deceptive musically because it causes the viewer/hearer to mentally associate that character with the typed letters. Sneaky!) By the time we get to Andover and the sign is zoomed in on, we get a very heavily-hammered A note. I was curious to see whether the same would hold true of the B, C, and D crimes. And sure enough– when the Bexhill poster is shown, we get a blaring B in the key of B minor, even– and later, Churston takes us to C minor! I was very giddy about this… 🙂 🙂 🙂 There are associations with keys for the different crimes in other places, too, such as when Donald Fraser is discussing the Bexhill crime and his dreams with Poirot, and the “ABC” theme plays in B minor again (B-C#-D).
Doncaster presents some interesting musical moments, too. The drone of the D for Doncaster begins when Japp, in Poirot’s sitting room, contemplates the St Leger as a complication of plans. When Cust enters the train to travel to Doncaster with the rest of the crew, we hear a “A-B… C-D”! And when everyone arrives in town together, sure enough, the key is switched to D minor.
I just want to hug the composer at this point. But moving along. 🙂
One of the most intriguing sections, musically, is when the crowds are congregated at the St Leger, and we see our various characters standing at their posts while Poirot parks somewhere to employ the grey cells. The music starts in A minor, and slowly modulates up by half steps through various keys, so that we get the B minor and C minor moments of earlier crimes as Poirot sits and thinks about them. This is also interspersed with Poirot’s own “regular” G minor theme. And just when he starts to get his revelation, what happens but a determined, final resolve to D minor!
We first hear the theme in F minor (I think) when Poirot is sitting and thinking about what will happen at Doncaster. Poirot’s denouement begins in his standard G minor, but when he gets to the part of his story where Cust meets the murderer over dominoes, the F minor key returns for the “ABC” theme. This is interesting– F for Franklin, perhaps? The reveal of the murderer takes us back to the original A minor, while the chase scene progresses through Ab minor, D minor, and F minor before returning to A minor. Franklin Clark is finally taken away by the police on a strong drone of F!!
Fascinating stuff!