It is about a pregnant woman who suffers from claustrophobia and is terrified that her unborn child might be feeling claustrophobic as well.
It was originally called ‘With Tall Walls Wall Me’ referencing Louis MacNeice’s poem ‘Prayer Before Birth’:
I am not yet born, console me.
I fear that the human race may with tall walls wall me,
with strong drugs dope me, with wise lies lure me,
on black racks rack me, in blood-baths roll me.
But the Litro editors suggested that this rather pretentious literary reference didn’t suit the tone of the rest of the story and I had to admit that they were right. The new title references The Sound of Music instead.