Nyssa opened the cupboard in the TARDIS lab where the medicines were kept and scanned the contents. As she turned to ask a question, she realised that Jake, who had been right behind her, was there no longer. She paused, then ventured back into the corridor.
"Oh," she said softly as she saw him. He leaned against a roundelled wall, halfway to his knees. His hands clenched against the edge of a roudel, his knuckles white. She couldn't see his face. But she'd seen something like this happen before. "Jake!" Her concern spiked when he didn't respond. "Jake, what's wrong? Is it the TARDIS again? Here, let me help you--"
She touched his shoulder and he threw her off with a guttural noise. She staggered, catching her balance only because her back hit the opposing corridor wall. The impact knocked the breath from her.
When she looked back up, he was standing without support. His back was to her, and it struck her immediately that his posture was very strange - very straight, with locked-limb, jerky movements like a rudimentary wooden puppet. His balance was not good, seeming almost to desert him at any shift in posture.
"Jake...?" Nyssa tried again cautiously.
Then he turned around, and her concern turned to fear. There was something about his eyes...
He took three long-limbed steps to reach her, and she could see, even in her fright, that his co-ordination was improving with every step. By the time he reached his hands for her, his movements were almost steady - and still very straight, and very purposeful.
She ducked under his arm and ran back down the corridor toward the console room. She didn't know where Tegan had gone, but thought her friend was probably resting. Nyssa had to get to the Doctor and Adric. The Doctor would deal with this.
She hadn't realised how fast Jake was. Fast like nothing she had ever seen, flesh or machine. An arm reached past her to slam shut the door in front even as another curled about her waist, stopping her painfully short mid-sprint. She was too busy gasping for breath to struggle much, and when she did snatch a breath she didn't use it for struggle.
"Tegan!" she yelled as loudly as she could. She could at least try to deliver a warning. She didn't want him to find Tegan in her sleep. "Tegan, run! Hide! It's Jake, he's gone--"
His hand closed over her mouth, and she hoped Tegan had heard. He carried her back to the lab, without particular effort despite the fact her feet dangled inches off the floor. Once there he shut the door, and bent a length of thick wire that had lain on a bench into two loops around her wrists. The material flowed like rubber in his hands, but she couldn't find in it even the slightest give. It wasn't twisted tight, but the loops were too small to slip over her hands. She hadn't realised he was so strong. He didn't use it, except by accident, in clumsiness. Frustrated and fuming now that the original shock had faded, she gave up.
Jake hadn't spoken. When she raised her head again, he was looking at her.
"Why are you doing this?" she angrily asked, as he turned his back - apparently he was satisfied, having watched her struggles, that she would not free herself. "Jake? Please - talk to me, Jake."
And it occurred to her then that he had not done that. Not since he was overcome with pain in the corridor had he spoken a word to her, as though language was incidental to his purpose. Then there was his businesslike manner and machinelike movements; passionless, inhuman. His eyes... What had looked out of them at her hadn't been Jake.
His headaches, she thought, hadn't been caused by the TARDIS.
"I know what you are," she said. It came out as almost a whisper. This was not the crisis she had argued with the Doctor about.
Her words made no impact upon his retreating back. "Jake." She ran the few yards across to him, tugging on his arm with her bound hands. He turned to regard her with impassive, minimal interest. "No... you're nothing like Jake, are you? But he's still in there. Can he hear me? Jake, can you hear me!"
Nyssa thought she saw a flicker of life in his eyes for the briefest instant before it died. But no, she concluded sadly, the control that had been established over him was too great. And she knew for certain now.
She whispered, unable to hide how the idea frightened and appalled her, "You're the ship's computer."
Nothing in Jake's borrowed eyes either confirmed, denied, or even acknowledged her. He pushed her away with a strength that wouldn't be denied, albeit no excessive force, and left the lab. The door closed and she heard him do something to the lock on the other side.
She was left to beat her hands futilely on the door, and just as uselessly shout his name.
Quite unconsciously, Adric found his steps quickening on his way back through the crashed warship to the TARDIS. When he realised what he was doing, it made him double-take, but didn't slow his steps by much. Apparently the Doctor wasn't the only one who was worried about Jake. But then the human had looked very grey when he'd stumbled off.
It hadn't taken the Doctor more than ten minutes to talk himself around to sending Adric after him.
The TARDIS door was open. That was nothing remarkable in itself - it had been open much of the time, as they were in and out. There was no physical threat here, after all, and as for any non-physical ones, well, the TARDIS had its own defences against those. But all the same Adric paused, feeling a small chill as though something undefined was wrong. He frowned as he encouraged his feet to ignore their better judgement and walk inside.
Nobody was in the console room, but he was almost immediately aware that he could hear running footsteps, gaining volume. A moment later, Tegan burst in through the interior door, looking a bit dishevelled and yelling "Nyssa!" in a breathless voice.
Her frantic eyes caught Adric instead and she stared at him blankly a moment before she burst out, "I thought I heard something. Did you hear anything?"
"Only you." He didn't see how she could reasonably expect him to hear anything else, wherever she was around.
"Have you seen Nyssa?" she snapped. "Adric, I'm worried - I thought I heard her scream. I think she's in trouble."
"What could she possibly be in trouble from, here?" He was about to go into detail about the TARDIS' defences, but he recalled his bad feeling of moments before, and didn't. He admitted, "I think something might be wrong, too." He looked around furtively at the empty console room. "Jake was supposed to come back here. If you haven't seen him, maybe something's happened to him, too."
Tegan grimaced. "Nanoboy? I definitely don't want to meet something that could happen to him! But I don't understand, there's nothing here! Unless it's another of those whatcha-call-its. Those illusions the Doctor said they tangled with before."
"It can't be," Adric said, "We just cut the power."
"Maybe you made something else mad!"
Adric nodded. It was as good a theory as any more scientific one he had to hand, since he had precisely none. "We should go back and fetch the Doctor," he declared.
"You fetch the Doctor. I'm going to keep looking for Nyssa."
There was no opportunity to argue with her, because Jake crashed through the door as though it had done something pretty awful to offend him. Tegan, who was closest, jumped sharply and backed off a step. "Jake? What the--?" She backed off several more steps as he turned to look at her, but Adric wasn't sure what she'd seen in his face.
"Jake, the Doctor sent me after you. We were worried." The words didn't seem to register. He watched Jake walk around the console, clearly aiming for the open door, and caught his arm as he passed close. "Wait, you can't go out. You're not well. The Doctor will be back soon, at least wait until then."
Jake broke his grip and shoved him away, using all the his enhanced strength. Adric yelped as he landed on top of the console. His feet had left the ground! He rolled off again, fighting dizziness. Looking up in astonishment, he finally had a full view of the human's blank expression - what Tegan had seen and absorbed already.
"We've got to stop him," Tegan said, with a peculiar hushed anguish, as Jake headed once more for the door. "Adric, you saw it - something's got to him. I think he's possessed." And he supposed that after Deva Loka, she would know if anyone would how to recognise the signs. "Who knows what's got him, or what it intends to make him do! We can't let it!"
"Don't--" Adric began blurrily.
He supposed too that it was her hypersensitivity to the issue after the Mara that fuelled her determination in tackling him despite the fact that - and he wasn't even going to waste his breath in pointing it out to her - the nanite-enhanced Foley was far stronger than one silly ordinary human female. Adric groaned. Jake hadn't even been interested in them. They could have let him go on his way while they found the Doctor.
He winced, watching Jake trying to throw Tegan off as she clung to his waist, his arm, his T-shirt, her grip slowly sliding despite her surprisingly good impression of a Seddarian limpet. All the while she was shouting, "Jake Foley! You're Jake Foley, from Earth! You have to remember who you are and fight this! Throw them off - you can do it, Jake!"
Adric didn't see any flicker in his expression to suggest her words had an impact, but he could see that Jake was - Jake's body was - gathering himself to strike her, and with that kind of strength, if he hit her then she wasn't going to be getting up again anytime soon, if at all.
Adric supposed he would have to help her. He surged to his feet and grabbed Jake's arm. It wasn't in time to prevent him sending Tegan flying, but it did absorb some of the force of the blow. He was aware of her on the floor behind him, dazed but moving. Now he just had to worry about himself.
He tried to meet the human's eyes. Tegan hadn't managed to make eye contact - perhaps that would get through to the real Jake, wherever he was buried. "Jake, you know she's right," he pleaded, as the enhanced human shook him, trying to dislodge him - Adric would've been all too happy to be dislodged if he'd thought there was any chance he wouldn't end up pasted against the nearest wall or ceiling in the process. "You have to remember who you are. We're your friends."
He could've hoped for that last to have more impact, but since mostly all he'd done so far in their relatively short acquaintance was to poke fun at the human's equations, he probably ought to have formed a more logically realistic prediction that it wouldn't. Instead, Jake tossed him into the wall with an audible, painful 'crack', scanned the room with his impassively controlled gaze, then continued on his way as though neither of them had ever stood in it.
Adric tried to rise to one knee and groaned as it proved to be just as ill-advised an idea as he'd thought it would. He fell back.
Nyssa stood in the door, her pale face oddly reddened in patches on the right hand side. Her arms were secured in front of her and there were obvious burns on her hands and arm from some kind of a laser cutter, and a sheen of sweat on her skin. Her eyes stared past them to Jake's vanishing figure, and returned glazed with a manic intensity.
"We have to warn the Doctor," she said. "Tell the Doctor that he has to stop Jake."
"Good luck with that," Adric said, pained, hunching over his ankle. "I think it's broken."
"I'll go." She lurched upright clutching her head. "You stay with Adric."
"What's the hurry anyhow?" Adric asked fearfully, sure that Nyssa had figured out something he'd missed.
"The warship's computer - it has control over Jake," she said. "I don't know exactly how, but... Tegan, a computer completes its programming. That's its function, it's mission. And we know this ship's last mission." If it was possible, she'd gone even paler. "There are at least a dozen missiles still capable of detonation on this vessel, and a whole population of the enemy out there. It can still complete its mission - it doesn't know this planet is at peace now. All of those people... we have to warn the Doctor and save them, somehow!"