From page 114!

Angus went down on his knees next to me, and I saw his face join mine. When we looked at each other, our reflections gazed off the corners of the room. When we looked over our shoulders our reflections locked eyes with each other.
“What is it?” he said softly.
“Damned if I know.” I sat back on my heels.
Our reflections didn’t vanish. They stayed where they had been, gazing up at us. As I watched, my face opened its mouth, revealing rows of pearl teeth, in a silent scream of horror.