They'd accidentally ejected the kitchen.

Not only the kitchen, but the pantry and the food dispenser as well.

The Doctor hadn't noticed this until they'd stopped for a breather after the whole ordeal on Castrovalva. He wasn't worried, though. It was simple enough to create a new room for eating and storing food. Getting a new dispenser, however, was a bit more difficult and time-consuming, but it could be done. The Doctor initially put it off at first, wanting to at least get Tegan home before he started another project. Of course, that didn't work as smoothly as he'd planned and they kept getting sidetracked everywhere they went.

After several weeks, he'd finally come to the conclusion that he really ought to do something about it. They'd been eating out or grabbing food on the go, but it was horribly inconvenient. Trying to choose a restaurant as a group was quickly becoming irritating, as everyone had different preferences. They'd already been banned from several establishments, and then Nyssa had gotten ill from fast food because her body just wasn't used to such a thing.

There was really no choice but to either fix the food dispenser or go grocery shopping. And so, the four of them ended up in a crowded supermarket on earth somewhere in the 21st century.

"Stop that." said Tegan.

"What?" asked Adric, reaching into a bag of crisps.

"You can't eat it in the store! We haven't even paid for it yet."

"But we're going to," he pointed out.

With a sigh, she snatched the bag from him and dropped it into their trolley. Just then the Doctor came up to them and put five or six bags of celery in the trolley. "...Are you sure that's enough?" Tegan asked, eying the vegetables.

"I think so," he replied, "After all, it's got to last until I fix the food dispenser."

Nyssa walked up behind him bringing several bags of produce. "Shouldn't we get more nonperishable items? All this might spoil in the meantime."

"Of course not! The TARDIS fridge can hold everything in stasis indefinitely. No rotting, no spoiling, and hopefully no more issues for a while." He moved to take control of the trolley. "This should be enough to hold us for the time being. Shall we find a checkout?"

The trolley was nearly overflowing with shopping for a group of four, and was heavy enough that he needed Nyssa or Tegan to help him around corners. He'd insisted that they only get the necessities, but after the first ten minutes of shopping and impulse buys, he'd also started adding random items to the cart. Why not? At least his friends were getting along and not wandering off into trouble. They eventually found a checkout that didn't have a long line, but there was no clerk. Instead, there was a scanner, bags, and a little screen with an animated shopper and some instructions.

"That's not a checkout." said Tegan.

"Actually, I think it is." The Doctor examined the machine. "Oh, yes...in this century, there's been a trend for self-checkouts."

"What, we're supposed to just ring ourselves up?"

"That's the general idea," said the Doctor, "You just take your item, scan it, and the drop it in the bag." He demonstrated with a tin of peaches and the little animated shopper on the screen did the same. "Easy enough." Seeing Tegan still wasn't on board with the idea, he went on. "Self-service is actually the norm for most grocery stores in your time. Up until the early 1900s, the employees did the shopping for you."

Nyssa looked around at the many other people in the store. "Really? That must have been horribly ineficcient."

"Not really. Shops back then were considerably smaller, often specialising in only one type of good. Customers gave their orders to the clerks, who would fill them and have them delivered. And then Clarence Saunders came up with the idea of letting customers do their own shopping, and well..."

"Okay," said Tegan,"but if there's no clerk, what's to stop someone from just bagging their items without paying?"

Adric grabbed a bag of bread from the trolley. "Let's find out." He dropped it into the bag.

Immediately, a small speaker piped up with "Unexpected item in bagging area. Please remove item and try again."

"I'd say there's a scale underneath that weighs everything you put on it and compares it to what the computer says it should be. If something doesn't match up, it won't let you proceed. Is that it?" The Doctor confirmed it. Satisfied, Adric removed the bread and waved it over the scanner. "Please scan your next item," said the voice.

"I am!" he replied, waving it faster. The animated shopper helpfully demonstrated scanning.

"You need to show it the bar code," said the Doctor, pointing it out, "And let's start with the heaviest items first so nothing gets damaged." With that, he put the bread back in the trolley. The others began digging out items from the trolley, passing them to the Doctor who quickly scanned and bagged them. Relatively quickly, that is. Between each scan he had to wait for the little animation to finish and the voice to instruct him to put the item in the bagging area.

Soon, the small space was full and he picked up one of the bags to put it in the trolley.

"Please return item to bagging area."

"Hmm?" The Doctor looked at the screen again. The little shopper was showing him how to put an item back.

"What's wrong?" asked Nyssa.

"I don't know." He tapped at the screen a few times. "I think we're not allowed to remove anything until the transaction's finished." The others looked at the rest of the groceries. The trolley was still very full, and by this time there were several other shoppers waiting behind them.

"You must be joking!" exclaimed Tegan.

The Doctor replaced the bag. "Well, I don't see any option on the monitor to let us take this bag off. Don't worry. I'll just stack things very carefully." He placed another item on top. And then another, and another...

He scanned and stacked a box of biscuits. "Unexpected item in bagging area," went the voice.

"What?" He picked up the box and put it back down, only for the voice to speak up again. "It's not unexpected, I just scanned it!" Once more, the biscuits were rejected. "Come on, it's on the scale. You can't tell me you don't feel that!"

Tegan looked at the box and noticed it was already open. "Here," she said, looking inside, "Of course it's not registering this. Someone's been eating them." She looked pointedly at Adric.

Nyssa paused halfway through her third biscuit. "Sorry."

The Doctor put the box back in the trolley. "We'll just do that one later. Now, how do you suppose we scan produce?" With bananas in one hand, he tapped a few keys on the screen.

"Por favor escanear el próximo artículo."

"Right. Not that one, then." He frowned. "We'll scan those later, too. Ah, I don't think we're allowed to proceed until we fix the problem with the biscuits."

Nyssa examined the screen for a moment, then turned and walked over to a lone terminal that was positioned to overlook all of the self-checkouts. She tapped something on that screen, and then the other screen unfroze to let them scan more items.

"How did you know what to do?" asked Adric as she came back.

"The employee who was standing there keeps going to help other people. It's a monitoring station of some kind."

The Doctor continued scanning. A few uneventful minutes passed as the stack grew taller and the helpful instructions grew more grating. Adric stepped in to help hold things once the stack started to wobble. By now, the cart was only half emptied. "Unexpected item in bagging area." said the voice.

"What item?!" asked the Doctor, "I haven't put anything else in!"

"Adric's leaning on the scale," said Tegan.

"I'm not leaning on it!"

"Unexpected item in bagging area."

"You're sprawled all over it!"

"That's because I'm the only thing keeping this stack from toppling over!" he snapped.

"Unexpected item in bagging area."

"You could help me, you know."

"Scoot over."

"I can't move, it'll fall."

"Unexpected item in bagging area."

"Well how am I supposed...? Okay, there."

"Got it? It's slipping!"

"I've got it!"

"Unexpected item in bagging area."

A box clattered to the floor.

"Please return item to bagging area."

"Rabbits. Nyssa, could you...?"

Nyssa picked up the box and put it back on the pile. "Do you need help?"

"Yeah, if you can get in here," said Adric, "Just try not to touch anything too heavily." Together, they awkwardly arranged themselves in an attempt to keep everything from falling without adding their own weight to the scale.

"Where do I need to hold it?"

"Just there...Adric, move over!"

"I CAN'T, IT'LL FALL!"

"Unexpected item in bagging area."

"Doctor," began Nyssa, "That woman who's supervising all this...she's not busy. Maybe you should ask-" Gravity won as the whole stack tumbled to the ground. The attendant, having heard the noise, hurried over to them.

"Excuse me, do you need help?" she asked. The Doctor stood among the spilled items looking completely lost. Tegan had fallen backwards and landed with several boxes in her lap, Adric chased after a few stray tins that were rolling away, and Nyssa had somehow slipped and gotten wedged in the bag holder.

"Unexpected item in bagging area."

"Erm..." said the Doctor, "Yes, we seem to have run out of room."

"It's okay, most people run into that problem. If you'll just watch the screen, I'll show you how to tell it to let you take out the full bags and get new ones..." She patiently explained the procedure, which was embarrassingly simple. Meanwhile, Tegan helped pull Nyssa free and Adric wheeled over an abandoned empty trolley to put the scanned items in.

"Thank you," said the Doctor sheepishly.

"Don't mention it. Are you here for the convention?" asked the attendant. When the Doctor didn't immediately reply, she clarified. "That sci-fi or whatever convention going on down the block? We've been getting cosplayers in here all day. Yours look really good, though. What characters are you supposed to be?"

Adric and Nyssa, overhearing this, looked at Tegan for an explanation. She just shrugged and looked at the Doctor, who was quickly running through plausible responses in his head. "It's...anime."

"Ah. I wouldn't know it, then. Never could get into that stuff. Do you need any more help?"

"Oh, no. No, we're fine," he insisted. "We'll just finish up here." After a few more repeated assurances that they needed no further help, the attendant turned to the grumbling queue behind them.

"We can get all of you over on Lane Six, if you'll please make your way there..."

As the irritated shoppers left, the Doctor crouched down to help the others pick up all the spilled goods. "Nyssa, could you pass me the bag that's stuck to your back? Thanks..."

Tegan and Adric had taken some bags and had begun gathering the items that had fallen the farthest before they could get trod on by the other shoppers. "This is ridiculous," he muttered, "why did we get so much stuff in the first place?"

"Because some of us eat too much," Tegan replied, picking up a few tins.

"I told you already, I'm a growing boy and I need to keep my strength up."

She scoffed. "Yeah, growing outward."

"Oh really? Well, I'm not the one who got all this chocolate, and the last time I checked Terran females tend to accumulate weight more on the hips and thighs."

"...shut up."

He smirked as she turned away. Glancing around his feet, he saw a colourful box and picked it up. It didn't look like anything of theirs. "What's this?" he asked.

Tegan looked up. "Those are mine."

"What are they?"

"None of your business. Give them here," she said, reaching for the box.

He backed away. "Not until you tell me what they are."

"Just hand them over!" she snapped, making another grab for it. He turned away and quickly opened the box. "Adric!"

"Seriously, what are these?" he asked as he pulled out an individually-wrapped package. He ducked around Tegan as she attempted to get the box from him again and unwrapped the item. "It's just a tube!" he exclaimed, "It's just a tube of cotton and string! What do you need this for? It's not even edible!"

"ADRIC!"

At this point, she was chasing him around the checkout area. He managed to stay a step ahead of her until she cornered him in front of the scanner. "Come on, what are they for?" he kept holding the box out of reach. "Just tell me!"

She told him exactly what the cotton tubes were for, a bit louder and more crassly than she'd intended to, judging by the looks she was getting from people nearby. Adric froze, completely speechless for once. Then, with a strangled sort of noise, he dropped the box like it was on fire. Cheeks burning, Tegan picked it up. "You wanted to know..." she muttered.

The Doctor, having heard the outburst, put the bag he was filling into the trolley and said, "Tegan, I've travelled with human women before. The TARDIS already has everything you need to deal with mens-"

"That's okay, but I'd rather handle it on my own."

"Handle what?" asked Nyssa. The Doctor briefly explained the situation while Adric desperately tried not to listen. "What, every month?" Tegan nodded. "Interesting. My cycle actually-"

"OH, LOOK. THERE'S ANOTHER QUEUE FORMING, WE REALLY OUGHT TO GET MOVING. DON'T WANT TO KEEP PEOPLE WAITING." suggested Adric.

This time, Tegan rung up what was left while the others finished collecting the groceries and putting them in the trolley. Finally, finally, the last item was scanned and bagged, and she could press the Finish and Pay button.

"Do you have a loyalty card?"

"Doctor?"

He stepped up to the machine and fumbled through his pockets, eventually producing a credit card which he inserted into a little slot. After a moment, he realised it was the wrong slot and tried the card in a few more places before he found the right one. Unsurprisingly, it was declined. "But it's good in any sector of this galaxy!" he protested.

Tegan, Nyssa, and Adric all exchanged looks to determine who would be the one to tell him. Instead, they decided to watch. He ran the card through a few more times, then started tapping at the screen in the hopes of unlocking the intergalactic capabilities of a 21st century checkout. "No, I don't want to add a coupon...no, I don't have a loyalty card! Not feeling particularly loyal, thanks..." Frustrated, he pulled out his sonic screwdriver and gave the machine a few zaps. "...well, that's done it."

The red light at the top of the machine started flashing and the attendant came over again. "Trouble?" she asked.

"Ah..." said the Doctor as she gently took the screwdriver from him and tried scanning it.

"I'm sorry, sir, the scanner appears to be broken. I'm going to have to call my manager."

"Oh, that won't be necessary," said the Doctor.

The manager was already coming over. He tried scanning the screwdriver as well, then looked at it. "Sir, someone's removed the bar code from this. I'm going to have to do a price check." He and the attendant went to the supervising terminal, the Doctor trailing after them. "Hmm..." he said as they fiddled with the computer. "Sir, do you remember which section you found this in?"

"Actually, I've changed my mind about that one. Nyssa? Would you go put this back for me, please?"

The Doctor passed Nyssa the sonic screwdriver and she walked off in the direction he'd indicated. Meanwhile, the manager had gone back to the checkout. Tapping the screen experimentally, he shook his head. "Afraid I've never seen anything like this, sir. I didn't know these things could even get static! If you and your friends will just come over to Lane Nine, I can get you checked out. But I'm going to have to restart the whole transaction. Sorry."

"It's quite all right."

"This way, sir."

They started following him when Tegan nudged the Doctor. "They're not going to accept your card. How are you going to pay for all this?"

He frowned, patting down his pockets. "Good question. I know I've got some currency, but not for this decade...or country. And I suppose bartering's no longer fashionable..." Tegan groaned.

Suddenly, there was a loud explosion followed by a blaring alarm and the entire sprinkler system going off. Around them, people screamed in surprise and a column of black smoke rose from somewhere in the middle of the store. "Attention, shoppers," said somebody on the loudspeaker, "Please remain calm. Locate the nearest exit and evacuate the premises immediately. Attention, shoppers..."

They were surrounded as hundreds of people began flooding the exits. Adric started to run the other direction and the Doctor grabbed him by the shoulder and pull him back. "Don't wander off!"

"But what about Nyssa?"

"You and Tegan stay here, I'll go find her."

"What if we lose you, too?" asked Tegan.

"Then I'll find you! Now wait here!" he turned around and ran into Nyssa. "Nyssa!"

"Doctor, I accidentally-"

"Hold that thought, we have to get out of here!"

Holding onto the trolley to avoid being separated, they made their way out of the store. Outside, they made their way down the block until the crowd thinned considerably. Tegan and Adric ended up pushing the trolley as they went. All four of them were dripping, having been thoroughly soaked by the sprinklers.

"Doctor," said Nyssa, "Here's your screwdriver. I was trying to hide it up my sleeve and I accidentally activated it."

"You must have bumped the wrong setting. Are you okay?"

"I'm fine, but I caused the explosion," she replied, concerned.

A fire truck sped past them toward the store. "I'm sure it'll be fine. Whatever you blew up probably wasn't that dangerous.

"Yes, but I was in the biscuit aisle. I blew up the biscuits."

"Oh." The Doctor was silent as he tried to figure out how his sonic could possible make biscuits explode. Nothing. He shrugged it off as a fluke.

They rounded the corner into an alleyway and went inside the TARDIS. "Right. You three get started putting all this away, I'll start the dematerialisation sequence and join you." It wasn't until they were back in the time vortex that the Doctor remembered that they hadn't actually paid. And technically they'd also stolen the trolley.

He made a mental note to just deal with it later.