I really appreciate your interpretation of this episode. I heard this show for the first time a few months ago and found it perplexing, but listened to it with "fresh ears" this week and did find it a meaningful, if rather strange and troubling, episode. I hear you suggesting that much of the story is allegory and symbolism and that approach adds a lot of weight to a story that otherwise might have too many loose ends. It would perhaps have been helpful to have more of the back story on the relationship between the doctor and Mary, rather than to just be told that they lack a strong connection. I was confused as to the plot element of having Mary refuse to tell her father anything about the "man" -- not even his name, but if we are not to see him as a literal person, this seems less important. If the girl indeed felt trapped and needed an "opportunity" to allow her to get out of the town, I am still a little puzzled as to why the writer thought death was the only option.

On a side note, I thought the music worked especially well in this episode for setting the odd, almost dream-like mood.