He doesn't seem to immediately be following, so Chell turns to look at her surroundings. At the sky. Lightening over at the horizon, stars slowly fading, wisps of cloud scudding past. It's huge. She'd forgotten how huge the sky is. When was the last time she saw the whole sky? She saw the moon through the roof, but--

The man speaks behind her and she whirls around, alarmed. She doesn't see a knife, and at first glance, she assumes he must be hiding it behind his back with the other hand.

Who am I? she signs, blinking. Who are you? Where am I? Are you going to kill me?