Birdsong

What do you do when one of the faceless, indistinguishable faces in the crowd refuses to fade out?

The memory of a face, a girl's face, has snagged itself onto Patrick's subconscious and is leeching into his consciousness. And he has no idea who she is.
She's haunting him. When he's awake. Or asleep.
Patrick starts seeing the girl everywhere. In his head, all the time.

He doesn't know what to do about it.
The girl- she's...just there.