"If you're listening to this, then one of us is going to die *voice warbling downwards*." Chilling, the story absolutely oozes with nihilistic, somber atmosphere. The first time I listened to this, when I was around 15 or 16, I mentally headcannoned it as one of the very, very last stories ten has before The End of Time. It's so grim, so without hope, and so quiet. I feel like the Doctor being unable to do much at all to change anything, to be unable to save anyone, really pushes him towards his destiny.