As soon as they left the TARDIS and stepped in the (freezing cold, Rose noticed) air, it became clear that something was very wrong. The Doctor turned to close the TARDIS doors, when with a defiant creak the doors closed themselves. The Doctor shouted out in surprise and rummaged frantically for his key. Rose found several items thrust into her hands from the Doctor's pockets, including a yo-yo, a stapler and a small tent. She barely had time to register shock for this before the Doctor found the TARDIS key and thrust it into the lock. Rose watched with growing dread.

"No no no!" the Doctor cried after a few moments, looking frantic.

"What is it?" asked Rose, knowing perfectly well what was happening but needing the Doctor to confirm it for her.

There was a pause. Rose sensed the Doctor was trying to come to terms with the inevitable truth. "The TARDIS. It's gone into lockdown."

"You mean... no way back in?"

The Doctor looked frustrated and bewildered at the same time. Rose's heart seemed to be in her throat. No TARDIS? No way home? A question was burning on her lips but she swallowed it down, not sure if she wanted to hear the answer or not. However, after a few moments the Doctor answered it for her.

"We can get back in," he said. Rose released a breath she didn't realise she had been holding. "But... I - we - need to find out what's made the TARDIS sick."

"The TARDIS is sick?"

"Very sick. Not a good sign. There's something in the air, something she doesn't like. And we need to get to the bottom of it. Come on."

They walked in silence for several minutes. Despite their predicament, Rose couldn't help but take in the scenery as they passed. On looking closer she noticed all the differences in this planet's scenery, and wondered how she couldn't have spotted it before. The trees were a purply-green, with tiny leaves in the shape of stars and moons. The grass was almost springy, and when Rose looked into the sky she noticed how clear it was. Not a cloud in sight. The air felt much fresher (and colder). An improvement to Earth in many ways, Rose thought to herself. Although the Earth didn't force the TARDIS to shut them out.

As they walked along, Rose noticed one thing that she couldn't help pointing out to the Doctor. "Doctor? It's getting dark," she said, noticing the skies become gradually grey before her eyes. Maybe the days were shorter on this planet.

"Yup," the Doctor replied, sounding more like his confident old self.

"Well, I know you like danger and everything, but I don't fancy spending a night out in the open air on a strange planet," Rose informed him, a slight edge to her voice.

"And you won't need to!"

"How's that now?"

"We have this." He was holding the tent he'd thrust into Rose's hands earlier.

Rose stared at it. "Camping? Well, I'm not a huge fan, but… I suppose it's better than nothing." She suddenly realised something. "Hold on - just the one?" she asked, her voice slightly higher than usual.

"Well, yeah, why what's wrong with that? I don't... oh," the Doctor said, realisation dawning on him. They stared at each other. Then Rose realised they had bigger things to worry about.

"Anyway," she said, waving her hand to brush it aside. "It's getting dark really quickly so hadn't we better put the tent up?"

"Yeah, yeah, come on, let's find a spot," said the Doctor enthusiastically. "Allons-y!"

They walked for another ten minutes, the sky's light fading fast. By the time they reached a location the Doctor deemed appropriate, a quiet section of clean grass sheltered by several trees, it was almost pitch black, and Rose was shivering violently. She stupidly hadn't brought a jacket or coat, and the night air was bitter on her exposed skin.

"Well, s-so m-much for the r-relaxing vacation I was a-a-after," she managed to joke, teeth chattering. The Doctor glanced at her, then instantly took off his long brown coat and wrapped it round Rose as best he could. Rose smiled.

"A-always the gentleman," she grinned. She jumped on the spot, trying to warm up. The Doctor took the tent from his pocket, and, looking rather dubious, started to unravel it. The cold didn't seem to be affecting him as much. Rose didn't question this; she had accepted his many differences a long time ago. In fact it made him much more interesting than most men she had known. What would it be like to be alien? she thought.

She heard a splutter of laughter from the Doctor, and realised she must have voiced that last thought aloud. If she wasn't so cold her face would have turned pink.

"Rose Tyler, an alien?" the Doctor pondered. "Although, if you think about it..." The Doctor paused, and Rose braced herself for the rant she knew was coming. "If you think about it, an "alien" is basically someone who's not from your planet, so I'm an alien to you, you're an alien to me - though one of the more attractive ones, remember the Slitheen? - so no one can ever actually call themselves an alien, do you see what I mean? No, you obviously don't from the look on your face and..." he trailed off. "You're staring at me again."

The look Rose was giving him exuded affection and exasperation in equal measure. She prodded him gently with her foot. "Oi, you, t-tent, remember?" she told him, still feeling cold to her bones despite the Doctor's coat being wrapped round her. The Doctor gave her a mock salute and resumed his actions. It was clear he was a novice when it came to putting up tents, and Rose wasn't much use as her fingers were so numb, so between them it took over twenty minutes before the tent was erected. Rose noticed that it was rather small.

The Doctor looked at Rose in slight concern. "Your lips are turning blue," he informed her.

"I'm n-not bleeding surprised." Rose shuddered. "Why is it so cold, anyway?"

"Wish I knew. But I know I don't like this planet. It doesn't feel right." He seemed to sink into a reverie for a moment, only moving when Rose prodded him again. "Sorry - go on, get in - you look like ice."

"Thanks, I think."

They knelt down and crawled into the tent opening. Rose was relieved to see that sleeping bags were included - they seemed to be attached to the tent lining, which was much softer than tents on Earth. Unfortunately, though, the tent most certainly wasn't bigger on the inside like the TARDIS. There was just about enough space for two people to lie down. Barely.

Rose slipped into a sleeping back as quickly as her numb body would permit, and sat there, desperately trying to warm up. The Doctor climbed over her rather awkwardly, giving her a sheepish grin as he did so. Rose noticed that he ignored his sleeping bag.

"This must be what hypothermia feels like," she joked to the Doctor. The Doctor didn't smile, but lifted his arm and put it round her shoulders, drawing her closer.

"What are you doing that for?" Rose was surprised.

"Body warmth, of course. And my body's warmer than humans'. Two hearts," he elaborated, when Rose looked confused.

"Ah," was all Rose replied, having no intention of challenging this point when she was in this position with the Doctor. Although it was just to keep her warm, she told herself.

"Plus…" the Doctor hesitated. "It's, um, likely to get a lot colder as the night goes on…" He flinched as Rose let out a shout of exclamation.

"WHAT?" she yelped in shock. "But I'm already becoming a human icicle!"

"Body heat can work wonders in a situation like this," the Doctor informed her, grinning widely.

Rose sighed heavily. "OK, fine. Anyway, I don't feel ready to sleep yet so… how are we gonna pass the time?"

The Doctor blew out a long breath. There was a long pause in which Rose stared up at him expectantly, still shivering slightly. "No idea," the Doctor finally concluded. Rose groaned loudly and the Doctor prodded her in her side, making her squeak. "Don't, that tickles!"

The Doctor looked delighted. "I found your weak spot! I'm making a mental note, Rose Tyler is very ticklish…"

Rose looked furious. "Don't you dare…" she said, prodding him back experimentally. The Doctor looked down at her and cocked an eyebrow, but didn't react. "Dammit. Oh well, I'll find yours eventually."

"I doubt it," was the Doctor's cocky response.

"Just you watch."

They chatted about nothing in particular for over half an hour, but Rose couldn't help noticing that she wasn't warming up. In fact her temperature was gradually dropping, despite being wrapped in a sleeping bag and having the Doctor's arm wrapped protectively round her shoulder. She had stopped shivering but found herself beginning to again. The Doctor, who had taken his screwdriver from his pocket and was fiddling around with it, didn't notice.

"This is h-horrible," Rose remarked matter-of-factly.

The Doctor looked surprised. "What is? I thought this camping lark was a bit of a laugh… maybe a bit more domestic than I'm used to, but –"

"No," Rose interrupted. "The w-weather."

"Still cold, are you?"

"Ice pop stylee."

"It doesn't affect me as much," the Doctor informed her, almost proudly.

"You c-can't do anything with your sonic to w-warm me up, can you?" she said half-jokingly, glancing at it.

The Doctor looked blankly at her for a second, then suddenly his face lit up. "Of course!" he yelled with glee, making Rose nearly jump out of her skin. "Well done, Rose! The sonic screwdriver can put a sort of protective film round you... I've not done it for ages though, not sure I can even remember how..." He ran his fingers through his hair. Rose scrambled out of her sleeping bag with difficulty.

The Doctor muttered to himself for several moments, then lifted the sonic to point it at Rose. "Got it. Setting 45F... or at least, I think it is..." he trailed off hesitantly.

"Oh, that fills me with confidence."

The Doctor ignored this and moved his finger to a button on the sonic screwdriver. Just before he pressed it, he lowered the sonic, struck by a sudden thought.

"You don't ... mind, do you?" he wondered. "I know you didn't like the TARDIS in your head at first."

Rose shook her head, although she did have to ask one thing. "No side effects are there? I don't wanna be walking around with three arms or something."

The Doctor's eyes widened as this mental image floated around in his brain. "Not a good look for you ... and no. No side effects. I don't think." He avoided Rose's eyes.

"You're doing a lot of thinking ... and not a lot of knowing, Sir Doctor." She couldn't help but grin at the memory. A recklessness took over her, and she nodded at the Doctor. "Go on, do your magic. I'm already uncomfortable so..." She had barely finished her sentence when the Doctor re-aimed the screwdriver at her and pressed the trigger. She closed her eyes.

It was a relatively pain-free but strange sensation, rather like being gradually wrapped in invisible cling film. Except, of course, she hadn't become mummified and was still able to move all her limbs. This feeling continued for about a minute, and when Rose was sure it had completely disappeared, she chanced opening her eyes. The Doctor was looking at her very intently. Rose saw a glimpse of something in his eyes that she couldn't quite make out.

"OK?" the Doctor said gently.

"Fine! Great actually... I feel really warm now... thank you," she said to the Doctor. He treated her to one of his biggest grins. "I'll let you know if I start sprouting arms," she added, as she clambered back into her sleeping bag.

Now that Rose was settled, her mind turned to their current sleeping situation, and couldn't help feeling pretty awkward about it all. She glanced at the Doctor and his eyes told her that he felt exactly the same. Rose tried to think of something that would take their minds off it.

"Erm... should we play a game?" she suggested half-heartedly.

The Doctor pulled a face. "Like what?"

"I dunno! Um... I went to Market?"

"Nah, rubbish."

"That weird alphabet game?"

"Rubbish."

"I Spy?"

"What would we 'spy'?"

"Good point." Rose racked her brains but couldn't think of any decent games to play in a very small tent. "I could always try and find your weak spot..." she said without thinking, and instantly regretted it. She felt her cheeks flare up.

The Doctor stared at her, eyes very wide. "Rose Tyler!" he gasped. "Was that an invitation?" On the surface he appeared indignant, but Rose noticed that his cheeks had gone very red too.

"I... no! No! Sorry, I was just... I dunno. Don't mind me." She groaned inwardly. Oh, really smooth. To avoid more embarrassment she lay down on her side, facing away from the Doctor. She prayed he wouldn't press the subject, as she couldn't come up with a decent explanation for what she had just blurted out. A few minutes later she felt the Doctor lie down beside her. She held her breath.

"Y'know... the last time I used the sonic to warm someone up was over a hundred years ago. Surprised it still works actually." The Doctor's voice was cheery. Rose smiled to herself. She turned on to her other side to face the Doctor who was propping up his head with his elbow, shifting back hastily when she realised how close they were. She could even make out the Doctor's scatter of freckles across his cheeks. She gave herself a mental slap and forced herself to speak.

"Oh yeah?" she grinned, tongue between her teeth. "And where was that?"

"Lovely place called Freton Glarbon."

"Come again?"

"Freton Glarbon! Great place. Ten times colder than this though," and Rose shivered at the thought. "My friend, Joseph, who I was travelling with, he was human too... so obviously, the weather was too much for him, he would have died without the sonic, and in fact he nearly did..." The Doctor drifted off and Rose watched his face harden as unpleasant memories entered his head.

"I'm sorry," Rose muttered, not knowing what else to say.

"Yeah."

Rose felt the need to change the subject. "What are we doing tomorrow then?"

"Whatever you like!" was the Doctor's eager response. Rose found it hard to keep track of his mood swings sometimes. "But first I need to explore the planet a bit, get my bearings and all that. Then maybe we can find out where and when we are."

"Would be useful," Rose agreed. "I'm not sure I like this idea of you being clueless as much as I thought I would."

"I did warn you," the Doctor told her, but he didn't sound annoyed.

They fell into a comfortable silence, and Rose felt her eyes beginning to close. Maybe she was more tired than she thought she was, and despite being in a tent she couldn't deny she was comfortable and (thanks to the Doctor) now very snug. Suddenly aware of the Doctor being able to watch her sleep, she opened her eyes and looked at him. He was lying down properly now, and as she looked at him he gave her a rather tired smile.

"Do Time Lords get sleepy?" Rose teased him, grinning.

"This one does. I guess I'll speak to you in the morning, many adventures to be had..." The Doctor yawned, looking slightly embarrassed about being as tired as he was.

"Night, Doctor."

He grinned. "Night, Rose." The grin froze on his face as Rose leant over and pressed a soft kiss to his cheek. She then swiftly turned on her side with her back to the Doctor, who was left looking at the back of her head with his mouth slightly open. Well, that was new, he thought. Very new. And... nice, very nice. He shook his head, feeling slightly punch drunk, and noticed that one of her hands was still on this side of her body, resting on her waist. Should he take it...? The urge was almost overwhelming, but the Doctor managed to decide against it. He was very close to Rose's hair spread across the pillow, and he could smell her strawberry shampoo. It sent a small shiver down his spine. What being in close proximity can do to two people, the Doctor thought. Especially to himself and Rose. Before he could allow this thought to develop any further, the Doctor had drifted off to sleep.