The Silo was burning hot, but the elation in his hearts didn't let him feel it. The rocket which professor Yana had worked so hard upon was flying away, towards the signal, towards Utopia. The Doctor couldn't wait to follow, to see what was there. It was bloody brilliant. The Footprint system, a simple gravity pulse, was so subtle. He was amazed he hadn't noticed it before. He and Jack ran back and forth, adjusting settings, power levels, and signals.

After their little talk the Doctor was wondering if it might be time to tell Jack. Not to open it, but to let him see, to understand what was going on. Why the Doctor was running. It wasn't enough that Jack was a Fact. Maybe, once they were back in a more manageable era - several trillion years in the past, perhaps - he'd talk to him.

There was the sound of someone running around the rumble of the engines and the control room. He glanced up to see Martha. She looked terrified about something. Maybe it was the engines.

"Martha, the footprint, it's a gravity pulse!" he grinned, hoping his attitude would calm her. " It stems down, the rocket shoots up! A bit primitive but it will take the both of us to keep it stable!"

He glanced at Jack, who shot him a grin. There was a beep at the console and he ran over, entering a line of code.

Martha followed. "Doctor, it's the professor. He's got this watch," she took a breath, "he's got this fob watch. It's the same as yours. Same writing, same everything."

He felt his breath stutter as he flipped several switches. He couldn't look at her. "Don't be ridiculous." Had Yana found Jack's watch?

"I asked him. He said, he's had it his whole life."

The Doctor felt his mouth go dry. He tried to concentrate on the computer, but his fingers were fumbling.

"So he's got the same watch," said Jack, dismissive.

"Yeah, but it's not a watch. It's this chameleon thing."

He wished she'd shut up. Too much talk about the watch, and Jack might start to wonder about his. Might open it.

"Nonononono, it's this, it's this," he stuttered, trying to word it. Jack was too close. "This thing, this device that rewrites biology. Changes a Time Lord into a human."

Jack stopped, his eyes wide. The Doctor stared at him. There was something there, inside him. Something was whispering to him. He could see it. Like a memory of a smell or taste or sound that he couldn't quite reach. With a feeling or rising horror, he saw Jack's hand pat at his pocket, subconscious. The console beeped, and Jack turned to it, flipping switches. Saved by the beep. The Doctor turned back to the console.

"And it's the same watch."

"Can't be."

"That means he could be a Time Lord," said Jack. "You might not be the last one!"

I know I'm not! Damnit, I know!

There was another beep. The weight of thousands of human lives was in his hands. He couldn't lose focus. "Jack, keep it level!"

Jack turned back to the computer.

"But that's brilliant, isn't it?"

"Yes it is, 'course it is. But which one?" His thoughts flew over the Time Lords he knew, who would run from the Time War. Hide as a human. The Rani. The Master. He started feeling hysterical. "Brilliant, fantastic, yeah. But they died, the Time Lords. All of them, they died."

"Not if he was human," said Jack.

I know!

The Doctor couldn't bear it. There was another. Three, now. Three, and one of them was an entirely unknown entity. He could be anyone. He gritted his teeth. "What did he say, Martha?" he looked at her, and a small piece of him hated her for doing this to him. She opened her mouth, but she was too frightened to speak. "WHAT DID HE SAY?"

She swallowed. "He looked at the watch like he could hardly see it. Like that perception filter thing."

He took a deep breath. "What about now? Can he see it now?"

She didn't reply, but he could read the answer by the fear in her eyes. Yes. Yana could see it. And even as he tried to think of something to say, a psychic awareness started to build in his mind. Something empty, and hollow, after being a wanderer for too long. It was like a creature rising from sleep, opening its eyes, not fully aware yet.

Jack's voice broke into him. The consciousness grew. "If he escaped the Time War then the perfect place to hide is at the end of the universe."

Martha was standing in front of him, looking like she was trying to console an injured patient. The Doctor wanted to scream at her.

"Think of what the Face of Boe said," her voice was desperate. "His dying words."

The rocket roared. The refugees were leaving off into their uncertain future. The silo shook, and he swayed with it. The presence, a hollow thing compared to what it once was when Gallifrey was strong and alive, felt huge within his mind. And he could feel the barest, familiar prickling of madness.

The Doctor looked at the screen which connected to Yana's laboratory. On the fuzzy screen, four letters were written in bold.

Yana.

You Are Not Alone.

The message from The Face of Boe had not been about Jack at all.