"You do?" the Doctor asked with a disbelieving snort. Right, of course. Had to make a run for it, that made sense, because he was the cause of---

No. No, it was the way Jack said it. The tone of his voice, the pure fear. Something was wrong, something that would terrify a fixed point. And, really, when invincible things were scared, it was probably a good idea to be scared as well.

"What's happening, Jack?" he demanded. "What does it mean?"