Sarah ran, ignoring the burning in her chest and legs. The meteor that Mr. Smith detected and alerted her to had suddenly started expelling some sort of toxic gas that set her watch scanner ringing like the church bells at Christmastime.

Fortunately, it was the middle of the night and she'd left the kids at home. She never would've forgiven herself if they'd been with her and in this kind of danger. She'd taken too many chances with them and had been lucky so far. She didn't know what effects the toxins would have on her system until she got home and had Mr. Smith do a proper scan.

Provided she made it that long. She could feel the chemicals burning her lungs, even if she didn't know what their origin was. Absently, she wondered how she could manage to get the meteor quarantined before it could do any further damage to the surrounding countryside.

She suddenly felt a heat surrounding her like a shell. She stopped running long enough to see an eerie glow forming a bubble around her. She looked around trying desperately to catch her breath and see or determine the source of the bubble. In the darkness of the countryside, everything was hidden. She resumed her running, the bubble continuing to surround her even as she progressed.

Suddenly, Sarah ran into the equivalent of a brick wall. It knocked her backwards, flat on the ground. Too exhausted from the running and the poison gases affecting her lungs, she just laid there and closed her eyes. 'I'm really getting too old for this sort of thing,' she mumbled, mostly to herself.

'Oh, come on Smith, pull yourself together,' a voice from outside of the glow responded.

The voice sounded vaguely familiar, so she lifted up her head to look around and then dropped it back to the ground when she couldn't see anything. She measured her breathing, using all her mental skills to visualise the poison air leaving her lungs while the fresh air of her protective bubble entered them. As she took several deep breaths, she couldn't fight unconsciousness any longer and succumbed to the darkness around her.

Sarah woke to a hand pushing her hair back away from her face. As her eyes fluttered open, she was met by a pair of green eyes, staring down at her, concern radiating from them. 'You all right, Sarah?' the newest Doctor asked. Without waiting for her to respond, he put a hand under to back to help her to sit up. 'You look all right. All systems go, so to speak, wouldn't you say?'

The Doctor quickly stood up, 'And before you ask, I've already taken care of the meteor, at least for the moment by putting a protective field around it as well.'

Sarah slowly stood up and absently put a hand on her chest, feeling her lungs expand as she continued to breathe. Finally, she felt her lungs cooling off. 'Doctor?'

'Yes?' he turned to face her. 'You have a million questions, I'm sure, and I'll answer all of them, but not here, not now. We have to get rid of that meteor before it does any more damage.' He reached down and took her hand. 'Come along, Smith, to the TARDIS.'

Sarah allowed him to pull her along to the TARDIS and was soon soothed by the ship's familiar surroundings. She simply watched as the Doctor flipped switches and spun dials. 'So, the meteor?'

'Ah yes, well, I'm taking care of that. I wrapped a force field around it, much the same as I did you. I needed to shield you from the zytronomous energy it was expelling. Much longer and it would've turned your little comfortable atmosphere into an inferno.' He looked over at her. 'It wasn't doing your lungs any favours either.'

The entire room shook, causing Sarah to grab a hold of the console. She looked over at the Doctor, but he seemed to be ignoring it. 'Sarah?' he asked, giving her an odd expression. The room continued to shake, finally Sarah couldn't stand up anymore. As she hit the floor, she realised it wasn't the room that was shaking. The blackness enveloped her once more.

The Doctor was at her side in an instant, his fingers quickly feeling for the pulse against her neck. 'Way too fast. Extremely, very not good, Sarah.' He frowned as he quickly scooped her up and carried her towards sickbay.

Sarah's eyes opened yet again, this time her surroundings indicating she was in the TARDIS sickbay. She looked over and saw the Doctor sitting next to her, his hand holding hers tightly. 'Welcome back, Sarah Jane.'

'What happened?' she asked softly.

'A reaction I wasn't anticipating. I thought getting you out of the toxins would do the job, however you must've inhaled enough to do a bit more damage. It was an after-effect, however, I've run several tests and all the indications are you're all right now.'

'It did burn a fair amount.'

'It would. Zytronomous energy is fiercely volatile, especially in the present of a certain oxygen/carbon dioxide balance. The one that seemingly is in abundance in your lungs. Fortunately, you didn't spontaneously combust. That would not have been attractive.'

'My vanity is thankful then,' she said with a weary smile. 'Good thing you were there.'

'Oh come on, Sarah. You know I'm going to do my best to take care of you.'

'Until my dying breath?' she asked.

The Doctor rolled his eyes and shook his head. 'Oh don't be morbid.' He then reached up and touched her cheek, speaking softly. 'Not your dying breath, Sarah, until mine.'