"Did it work?" Jenny asked, climbing out of the underbelly. She beamed, as she noticed a new set of displays illuminating with newfound life. "Oh, look at that! I'm cleverer than I even knew!" She did a little dance in place to celebrate.

"They say they're ready on their side," Yimi told Jenny. Her eyes were fixed on the largest holographic display — showing footage of the room with the chameleon arch. The Doctor securing Seo into the chair, speaking to her animatedly. "It won't hurt her too much, will it?"

"Probably won't hurt her at all," said Jenny, reconfiguring some of the settings on one of the far panels. "The chameleon arch doesn't really function as a chameleon arch anymore. We're just using it to put Seo back together. And since machines can actually detect her when she's in little bits and pieces like this, the chameleon arch will examine each of those bits and pieces as it reassembles her, match them against our programming here, and use them to figure out what to delete and what to keep when it reconfigures itself from a vault back into the prison it should be." Jenny ran to the next panel over, and reconfigured those settings. "But, like Dad said — that's the easy bit. The hard bit's what we get to do next. Is Zeera disconnected from the telepathic circuits yet?"

Yimi closed her eyes. Then nodded. "Disconnecting now. I suppose I should join her."

"Probably a good idea, considering what we're about to do." She noticed Yimi's unease, and put a hand on Yimi's arm. "Yimi — I promise, we will save your people. One way or another, we'll make sure they're okay."

Yimi opened her eyes and met Jenny's. The worry did not leave her, but she nodded.

Jenny smiled, then spun round and ran over to the central console. "Okay." Took a deep breath, crossing her fingers. "Let's do this."

Then she threw down a lever.

The moment the lever was thrown, the Seos scattered throughout the vault began to vanish — one after the other after the other.

Then the Battle TARDIS shuddered. Its internal dimensions rumbled, as mechanisms and systems long since abandoned began to reconnect and reconfigure themselves. The dimensions began to rearrange themselves, as the basic programming of the TARDIS slowly changed.

And, as each slice of Seo was reassembled, the interior of the Battle TARDIS began to return to its previous state — as a prison.

Mutajar screamed.

Doubled over, hands on her temples. The pain! The noise!

"No! No!" Mutajar grabbed hold of the Doctor's TARDIS, clawing at the wooden panels, struggling to stabilize herself. "I can't...! I won't...!"

But she could feel the sting from the chameleon arch, just as she had so many centuries ago, when she'd nearly escaped. It was working again — pulling at her, yanking her inside out.

"The telepathic circuits," Mutajar breathed, staggering back into the Doctor's TARDIS. "They hooked the chameleon arch up to the telepathic circuits!"

She'd known they were in the room with the chameleon arch. She had known they were up to something in there. But she'd assumed they'd be far too busy using the arch to reassemble Seo or reconstruct Bivazeer's past. She should have known they'd find a way to do everything all at once.

She reached out to the two TARDISes at her command, frantically trying to disconnect her mind from the telepathic circuits. But she couldn't. She was trapped, and they were draining her away... draining her very essence into a fob watch, with nothing to replace it...

"No, don't worry, my swarm," she told the others, holding out her hands. She swallowed down the pain and focused herself. "I shall be fine. This is nothing. It will pass." She bit her tongue to stop another howl of pain. "I have already sown the seeds of their defeat. I just have to be a little more proactive in deploying those seeds — that's all."

She returned into the Doctor's TARDIS, and held her hand against the telepathic circuits.

Seo jolted in the chair.

Then, as if plunged into a world of pain, she began to scream.

"Is it supposed to be doing that?" Kardeni asked, running over to the chair. "I thought you said it wasn't going to hurt her!"

"I did say that, didn't I?" the Doctor mused. He took his hand away from the chair, revealing where he'd been fiddling with the settings. "I don't know why. After all, I configured this chair to connect to the telepathic circuits and delete anything that's vaguely Seo-like from the system. Only natural, given that she's from the Axis, and we're trying to reconfigure this place to be a prison." He shoved his hands into his pockets. "Thing is — it'll delete her, too."

"What?!" Kardeni ran over to the chair, struggling to undo the straps. "We have to get her out of there! We can't...!"

A glowing bird dove at Kardeni and she shrieked, dropping to the ground to avoid its swoop. It swerved around and landed on the Doctor's shoulder.

Kardeni looked between the Doctor and the bird. "Oh no..."

When the Doctor spoke again, his voice was mixed with Faye Mutajar's voice. "Did you really think you could defeat me a third time, Bivazeer? Did you really think your friends would be immune from my influence?"

Kardeni began to tremble, as more birds appeared around her, encircling her, their talons sharp, their feathers fiery, their intent murderous.

"Listen, you have this wrong," Kardeni insisted. "I'm not..."

She shrieked, as another bird dove for her.

"I have spent eons fantasizing about your death, Bivazeer," said the Doctor, his voice mixed with Mutajar's voice, as he returned to the chair and began to fiddle with it again. "I will hunt down and take from you everything you ever loved. Eviscerate friends and family alike. Tear apart the worlds you felt... safe..."

The Doctor stopped fiddling with the chair. Then he doubled up, hands on his head, teeth gritted.

"Get out of my head!" the Doctor shouted in his own voice.

Kardeni began to run forwards. "Doctor? Are you still...?"

But that was when the birds attacked.

"Something's wrong," Yimi said, as the ship began to shake violently. Warnings blared up on all panels, and she could see a flock of birds appear on the holographic projection where Seo, the Doctor, and Kardeni were. "Jenny, what can we...?"

Jenny threw herself at Yimi, attempting to bludgeon her with a hammer. Yimi darted out of the way, then leapt at Jenny, overpowered her, and yanked the hammer out of her hand.

One of the panels erupted into sparks.

"What have you done?!" Yimi shouted.

"Bivazeer has to be taught a lesson, Yimi," Jenny insisted, shoving Yimi off of her and jumping to her feet. "We all have to die in front of her, Yimi. Everyone has to die in front of her. That's the whole point."

She ran for the control panels.

Yimi tackled her to the ground again, head-butting her — but it didn't work. Jenny tried to claw at Yimi's eyes and Yimi yanked herself back, keeping hold of Jenny, sending them both into a roll across the floor as they struggled. They stopped rolling as they collided with the open toolbox. "Jenny, this isn't you! It's...!"

Then Yimi cried out, as she felt something try to stab into her own mind. And she was taken by the fact that it was so oddly familiar — something she'd let in more often than she knew. But now...

Where once, it had eased gently into her psyche, now, it tried to grab her mind and throttle it. She struggled to maintain control. Struggled against the foreign influence...

She heard Seo scream.

She looked up, and Jenny broke free and ran to the central console, frantically jabbing at buttons. More warnings flashed up around them, surrounding them with sirens and beeps and blares.

"No, no, it's no good! Jenny's only fixed this thing enough to fly to Galia-4 and then jammed the controls!" Jenny pounded her fist against the central console in outrage. "If I ever get my hands on that miserable progenitor-machined snot-worm again, I'll throttle Jenny to within an inch of her life!"

The Doctor kept reaching for the chameleon arch chair, then snatching back his hand as he struggled against the influence in his mind. "Have to... save..."

But every time he reached for the chair, he could feel himself beginning to reprogram it so that it'd kill Seo even faster and feed all Seo's powers and strength to the Apos'alu. He snatched his hand back again. No — he wouldn't do that. The Apos'alu with the powers of a dimensional Key! That didn't bear thinking about.

Kardeni shrieked, struggling against the flaming birds that scratched at her and tried to strike her.

Interesting that they weren't tearing her limb from limb though. The Doctor knew they could. And he knew how much the Apos'alu loathed Bivazeer...

"That's it!" the Doctor cried, raising his finger in the air. "You can't kill us! Neither of us." He felt his hand back on the chameleon arch chair again, reprogramming it — and snatched it away. "You're not up to full strength yet, are you, Apos'alu?" He gestured at Seo. "This was your insurance policy. You slipped it into my head without my realizing it. But even if it kills Seo — it still drains your essence. And you still haven't figured out how to take me over long enough to stop that!"

The birds fluttered their wings angrily, but still didn't do any permanent damage to Kardeni.

"And if you kill Zeera," the Doctor continued, "it'd release a torrent of grief and pain from this TARDIS that'd knock out your psychic manipulation full-stop."

"If I'm so weak, Doctor," said Kardeni — but her voice was mixed with that of Faye Mutajar, "then why are you altering the arch's settings already, while I gain strength?"

The Doctor realized his hand was back and he yanked it away.

Kardeni laughed. Around her, the birds reluctantly stopped their attack and circled her, eyeing her up and down with barely suppressed fury. "I've already taken over Bivazeer. The Patasi traitor will not be far behind. Your plan has failed, Doctor."

"Then why am I still alive?" the Doctor challenged. "Why is Zeera still alive?" He tried to regain enough control to take a step away from the chameleon arch — but couldn't quite manage it. "You're hooked into the telepathic circuits of both the Battle TARDIS and my own TARDIS, Apos'alu. Using the symbiotic nuclei, it'd be no great feat to take over my mind or Zeera's mind. You're bluffing."

The birds squawked. One dove at him, a second swiping at him with its beak, a third scratching at his chest. The Doctor tried to move to duck their advances, but couldn't. His skin burned beneath their fiery feathers.

He realized he was back to reprogramming the chair and yanked his hand away, shoving it behind his back and praying it would stay there.

"All you're doing by resisting, Doctor, is ensuring that Seo dies," Kardeni said with the voice of the Apos'alu. "And the chameleon arch won't drain my essence unless someone's strapped into that seat. So the choice is yours — submit to me and your companion lives. Resist, and she dies."