Jack stared out at the corridor around him, at panels in shadow and shades in the floor, looking out for anything that might trip them up. He had the distinct feeling they were being watched; the hairs standing up on the back of his neck and a cool chill running down his spine.

The voice turned his head. He spun his gaze quickly away from the surroundings and looked ahead. She looked so real, Donna in the light, Donna standing in front of them. But it couldn't be.

"Doctor..." Jack said his name like a warning and stepped forward, a hand out in front of the Doctor, protective.

"It's not her, Doctor, it can't be."

But it still looked so real.