The source sounds like it's just on the other side of the outcropping, and the sound is strained and shuddering - wounded, trying not to be obvious, too damaged to succeed.

But when he rounds the corner, for a moment, there's nothing.

Then there's Yelena, face set in a mask of grim determination, knife in hand, lunging at an older woman, dark-haired and olive-skinned. They are both faintly translucent, movements silent, like a holographic display with the sound turned off.

There's a strange sense of weight here, like it's somehow more solid than the corridors above, haunted by lost girls.