Gwen had gone with her heart and was now following the Doctor. Before they had left the outpost, they had managed to slip past the guards and into the building holding the bodies of the Master and Ashena.

She wasn't sure how they had got past them, but she guessed it was something the Doctor had done; but she wasn't about to ask.

He was muttering in his own language as he fussed with Ashena's hair and then took the blade she had used to kill herself. He moved onto the Master and said what she thought were the same words and then took the signet ring from the Master's finger.

Now they were crossing the same piece of ground that only hours ago had been a battlefield. Now it was deadly quiet, nothing but the dead and the still frozen creatures.

Gwen went to touch one but the Doctor's voice stopped her.

"Don't, their armour is covered in poison. It leeches through the skin, you take two days to die...in agony."

"Lovely, what do you call these things?" she asked as they weaved their way through them.

"They're called His'ra and you better wish they stay frozen. Come on, Gwen Cooper."

Jack was cursing himself for letting Gwen stay. He was angry that he'd allowed his feelings for the Doctor to overrule his caution.

He had a pretty good idea as to where the Doctor was going...he had to stop him...stop him using that infernal machine; if it still worked. He'd taken only Ianto with him, he wouldn't sacrifice another person. They cautiously made their way through the army of still frozen creatures and he warily watched for the twitch of an eye or a fang filled mouthed.

As the suns were rising they reached the entrance to the caves, now ripped apart by the creatures. He turned to Ianto and said. "You don't have to go any further."

Ianto shook his head. "I've fought beside you for twenty years, if you think I'm staying here, besides, I don't think the Doctor's going to come willingly."

"No, I don't think he will," Jack said and with that entered the cave.

The Doctor was impressed with Gwen Cooper; she had kept up with him...which was why he felt a twinge of guilt at what he was going to do.

He turned to her and asked. "Do you have something that belonged to Rhys?"

She gave him a sharp look. "Why?"

"Don't ask why, do you have something?"

"Not until you tell me why."

He let out a growl of frustration. "I don't have the time."

He reached out and touched her forehead and said. "Sleep," and caught her as she fell forward. He lay her on the ground and searched her until he found what he wanted.

"I'm sorry, Gwen Cooper," he said as he pocketed the item and turned away; he never looked back.

He could see what was left of the His'ra camp and beyond that the ruined warehouse and inside it, the machine.

He could feel it, even from this distance...the hum of power; the malevolence of it and the price there might be have to be paid.

But he didn't care...he wanted them back; his beautiful daughter and the Master. Insane or not, he loved him; he was the father of his children...how could he not.

"You're doing the right thing," he said, more to quieten his conscience than for comfort.

"No, it has to change."

He hurried through the deserted camp, knowing that Jack would probably not be far behind.

As he approached the destroyed building his stomach fluttered and his hearts raced.

The pull of the machine was even greater and without hesitation he began clambering over the rubble.

He never noticed the two figures emerge from the tunnel.

It was Ianto who spotted Gwen and they ran over.

Jack put his fingers on her neck. "She's okay, just out cold. I think she'll be out of it for a while."

He stood up and looked out over the open space. He narrowed his eyes as he spotted a distant figure, just as it disappeared behind a pile of rubble.

"Come on," he said to Ianto. "She'll be safe here."

They clambered down the slope, slipping and sliding in their haste to catch up.

They ran across the dusty ground and through the deserted camp and started climbing over the rubble.

A deep rumble shook the rubble and they had to stop.

"No...oh no, the machine," Jack said and throwing caution to the winds both of them jumped into the hole that the Doctor had disappeared into and into the corridor that led to the generator room.

They wasted valuable time negotiating the fallen beams and pieces of concrete, but eventually they entered the generator room, which seemed relatively untouched.

Below their feet, the generators were vibrating with power, giving life to the machine at the other end.

They could see flashes of light in the windows and they burst through the doors, expecting to see the Doctor inside the machine...but he wasn't; he was standing outside it, staring at the green tendrils that flicked like serpent tongues.

Jack moved forward, slowly, unsure of what Doctor was present.

He went to speak but the Doctor spoke first.

"You think you'll do anything for the ones you love, fight any evil...traverse galaxies...universes even...change a world. You'd even lay down your lives for them. But then something, who knows what...cowardice, fear, makes you hesitate."

He reached out a hand and one of the tendrils almost touched it, but he drew it back and it crackled in annoyance.

"Don't," Jack said. "That machine...its evil."

The Doctor laughed and then turned and looked at Jack and he could see the indecision on his face.

"Gallifrey or Earth, which is the lesser evil? I could change everything, bring them back. That's the power of this machine...the power of the gods."

He took a step towards it.

"Doctor, don't."

It was Ianto who spoke. "I can't understand the pain of losing a child but I can understand losing someone you love. You have to let go and move on and live with whatever that brings. Life is unfair, even for Time Lords."

The Doctor glance at him and then at Jack. He let out a breath and said.

"Well, I can't," and stepped into the machine.

"NO!" both of them cried and reached for the Doctor.

But it was too late and the tendrils wrapped themselves around the Doctor.

The floor beneath began to shake and Jack suddenly doubled over.

"Dear god...he's doing it...he's changing it," then he blacked out.

Ianto could do nothing as the machine increased in power and the Doctor began to scream.

Then he was blinded by a flash of light and then blackness took him too.