Jack processed the Doctor's words and repeated them over in his head. He thought he understood what the Doctor was telling him, but... he must be misunderstanding, mustn't he? That couldn't be right.

But the Doctor's face. That look.

He took another look around him, taking in his surroundings more thoroughly, the rock they'd climbed from and the colour of the grass, and that tower in the distance that the Doctor was gesturing to.

"But this..." Jack frowned, "that can't... this isn't? This..." he took a breath, and wondered why he felt so scared, maybe it was just residual from the drugs.

"Doctor..." he started again, more evenly, "are we on Gallifrey?"