The Doctor could have sworn he had detected another TARDIS. The readings were anomalous, and perhaps had been thrown off by the utter chaos in London.

At any rate, the trace was gone.

He would have to get back to Gallifrey as soon as he told her she couldn't come.

She had been crying, alone and abandoned in the vast ruined house. Those big brown eyes, so trusting and devoted. How could he leave her behind in this awful place?

"All right, you can come," the Doctor checked the nametag on the dog's collar, "Rose. I hope you're TARDIS trained."