One of my favorite episodes of the original Star Trek and, I would argue, one of their best overall episodes, was the action-packed season two entry, “The Doomsday Machine.”
A significant factor on why I believe it should be ranked so highly is because of the episode-specific music composed by Sol Kaplan. Viewers may recall the original series re-used a lot of music cues as a cost-cutting technique. The fact that they don’t do so here underscores (pun intended) how a composer can really bring a story alive.
Composer Shem von Schroeck has an hour-long video that goes into the music and the episode in depth. The first 10 minutes are discussing and demonstrating some of the themes Kaplan uses. The next 50 are a special annotated version of the episode itself, highlighting which music is used when. It really gives you an appreciation for how much art and craft goes into composing for the screen.