Lucille Fletcher, one of the greatest scriptwriters of the twentieth century, wrote a number of scripts for the radio series titan, Suspense. Her most famous is "Sorry, Wrong Number", but "Fugue in C Minor" is excellent as well. Fletcher was a music librarian for some time, and her first husband was an orchestral composer, so this music-themed horror story does much more than use music as a bit of dressing; "Fugue in C Minor" integrates its music and sound to create an odd but absolutely unforgettable story.
And everything else comes together for the episode, which first aired June 1, 1944. The soundwork is excellent; this is a story very much meant to be heard. The pipe organ itself basically functions as a character in the story. Theodore Evans is played by no less than Vincent Price, and it's a role that gives him room for his full range of acting. Ida Lupino plays Amanda Peabody. Evans's children are well done, and it's handled in such a way that their contribution straddles the line between creepy and sympathetic.
It's a popular episode. You can find it uploaded many times on YouTube:
You can also find it at Internet Archive (number 84).