A Highly Illogical Situation

"I'll be right there." Sherlock informed, taking the phone away from his ear and ending the call to Lestrade. He stood up, walking to the door and removing his coat from its home on the hook on the back of the door.
John walked down the stairs from his bedroom on the second floor. He really had drawn the short straw when it came to bedrooms. Initially, he was to have the first floor bedroom- much to Sherlock's annoyance- but after their first case, where Sherlock had somewhat cured his psychosomatic limp, he had no excuse as to why he had to have the first floor room. John still tried to argue, but soon gave up, as going along with it was a lot less painful than dealing with Sherlock.
John reached the living room and saw Sherlock begin to tie his scarf. "Where are you-"
"No time to ask questions. Are you ready to go?" Sherlock interrupted.
"I'm in my pyjamas!"
"Your point being?"
"I am not leaving the house in pyjamas!" John exclaimed. "Just because you are perfectly fine with going to Buckingham Palace in a bed sheet, doesn't mean I will."
Sherlock rolled his eyes and sighed, lifting his arm to reveal his watch. "You have approximately seven minutes." John furrowed his eyebrows, unsure whether he was being serious. "Chop chop."
Sherlock waved John off and sat himself on the sofa, picking up a newspaper. John stood still for a moment, but soon obeyed. Since day one, John had known living with Sherlock Holmes would be the most difficult experience, but he would sooner live with him than with anyone else.
Seven minutes and twenty-seconds later, John came rushing down the stairs once more, this time more suitably clothed.
"Twenty seconds too late." Sherlock announced as he threw the newspaper down on the coffee table.
"I would have been earlier, but the shirt I wanted to wear wasn't in my room."
"Which shirt was that?" Sherlock stood up, pushing past John out of the living room door. John followed.
"The white one with the blue pinstripe."
"Ah, yes. I had to use that last night to wipe up some acid that spilt while I was experimenting." He shrugged, skipping down the last flight of stairs.
"I'm sorry; did you just say that you used one of shirts to clean up acid?"
"Yes. I couldn't find anything else to use."
"You went from the kitchen, all the way to my room, and you couldn't find anything else?"
"There were no kitchen towels and I was hardly going to use one of my own."
"Of course not." John sighed.
They walked out into the street, hailing the nearest cab. The flat was in the most convenient place for them, as Baker Street always seemed to be saturated with taxis. The taxi pulled up at the curb and they got inside. After a few minutes, Sherlock glanced over at John.
"You've got questions." He said, looking out the window again.
"First of all, what are we doing?" John asked.
"We are in a taxi, John."
"Why, thank you, Sherlock. I would never have guessed."
"You did ask." He shrugged.
"I mean what are we doing as in where are we going? Is it a case or what?"
"Then why didn't you just ask that?"
"You really are insufferable."
"Case. Children going missing at Kings Cross Station. Or so they say. According to the witness, a bunch of children walked through a wall at the station and disappeared."
John's eyes widened. "But that's crazy! Who is this witness?"
"Just a passenger. Tests say he isn't insane."
"So you plan on explaining the disappearances?"
"I hardly see how I can do that, but Lestrade wants me there for some reason."
"Right." John nodded.
It wasn't a long journey to Kings Cross Station, so it was easier for John to stay completely silent for the next five minutes. When they arrived, John paid the taxi- as Sherlock had once more forgotten his wallet- and they walked onto the platform. It was crowded with people, as expected, but nothing seemed out of the ordinary. There were business men and women rushing around with briefcases, small children trying to keep up with their parents and occasionally a small argument breaking out if people collided. As they walked along, narrowly avoiding the bustle, they came to Platform Nine where Lestrade was stood staring at the wall.
"How can I be of assistance?" Sherlock asked, walking up behind Lestrade, which caused him to jump.
"Oh, you're here already." Lestrade turned round.
"We would have been earlier, had someone not taken so long." Sherlock added a glare to John at this point.
"I wouldn't have taken so long if someone hadn't used my shirt as a towel." John crossed his arms.
"Anyway, the case, Lestrade."
John stood back, listening only to the story, instead of the recent police report. Lestrade informed them that the man observed a family of five simply run through the wall only an hour ago. Apparently, their parents were there too, but didn't react at all. Sherlock seemed baffled, which was highly unusual, but he was still determined that he could somehow figure it out.
"So you say it was this wall here?" Sherlock finally questioned, pointing to the wall of Platform Nine.
"Yeah."
Sherlock walked up to the wall, looking at it from afar, circling around it to see every aspect. John knew that Sherlock always got close to things when he inspected them, but this was beyond what he was expecting. When Sherlock got back round to the side where Lestrade and John were, he leant against the wall, and seemed to just fall through it. He appeared to simply be absorbed by the wall.
"Sherlock!" John called.
He got no reply. John ran up to the wall, putting a hand against it. He asked as his hand disappeared into the wall, the same way Sherlock had. He gave it a minute of thought before walking through himself.

As John reached the other side, the sound of a steam train and excited children filled his ears. He looked up at the sign on the wall behind him: Platform Nine and Three-Quarters. To his left, he saw Sherlock stood stiff, glaring down at all the commotion that was clearly too close for his comfort. Sherlock turned to see John, which calmed him slightly, and said a single order before walking towards one of the train doors.

"We're getting on the train."

John could only obey.

On the train were thousands of adolescents, walking up and down in black capes until they found an unoccupied cabin. Every now and then they heard the muttering of what seemed like made up words, which seemed to make sense only to them. Out of nowhere, a golden firework-like spark came hurtling in front of them. Sherlock had only seconds to avoid being hit directly by it. The sounds of startled owls rang out, along with the shrieks of cats and croaks of frogs. John concluded that this certainly wasn't any ordinary train, nor were they ordinary children.

"This isn't-" John began.

"This isn't possible. I know."

"I don't know how I feel about this."

"Well, I did get a feeling of uncertainty as I happened to fall through a wall."

John could only weakly smile at this, as he was still in a state of shock.

"Sir, my toad's gone missing again!"

They both turned round simultaneously, realising the boy behind them was actually asking for their help.

"And you are?" Sherlock had to ask.

"Neville Longbottom, sir."

"Looks like we have a toad to find." Sherlock smirked, as he always did at the prospect of a new

case. It was a peculiar one, sure, but it was something to solve nonetheless. Without warning, he strode off to find clues. John followed behind.

"Another case about an animal, wonderful." He muttered to himself.

By train set off, almost twenty minutes later, they were no closer to a solution. They had seen more than a hundred different toads so far, but none of them were Neville's.

"Neville!" A voice shouted from a cabin ahead. The three of them faced the red-haired boy, seeing him stood there holding the presumed toad.

"Ron! You found him!" Neville called.

"The Doctor wouldn't be happy." Sherlock muttered to himself as they slowly walked closer, in contrast to Neville who was clumsily running.

John furrowed his eyebrows. "The Doctor?"

"Old friend of mine." John looked bewildered at Sherlock's statement, but didn't get chance to reply.

"Thank you for helping me anyway, Sir." Neville smiled at Sherlock, to which Sherlock responded only with a nod.

"Is that the new Defence Against the Dark Arts teacher?" The red-haired boy whispered to Neville, but it was still audible.

"Defence Against the Dark Arts?" Sherlock asked. "Is that some sort of lesson of combat?" The young boys scoffed.

"If only!" Ron exclaimed. "Last year we weren't even allowed to use magic!"

Sherlock and John stared blankly, thinking over and over as to whether he had heard them right.

"Blimey, you two look like you've been hit with a Body-Bind curse!" Ron laughed, digging his elbow into Neville's side. Neville didn't seem to find it as funny.

"They aren't magical." He whispered.

"What do you mean?" Ron was still cheery, thinking this was his idea of a joke.

"They aren't wizards, Ron." was all Neville managed to mumble out.

Ron's face dropped as he contemplated his next move. "But they have to be! How else could they get to the train?"

"I-I don't know."

"Well," he nodded reluctantly. "They'll enjoy Hogwarts!"

And with that the two boys ran off leaving Sherlock and John completely speechless. They attempted to run after them, but Neville and Ron were nowhere to be seen.

"I need to sit down." John mumbled.

For the next few hours, Sherlock and John stayed in an empty cabin towards the back of the train. John continued to feel uneasy about the whole experience, and Sherlock sat in his signature pose while trying to discover the logic behind everything that was happening. Unfortunately, he was getting nowhere. When the train began to slow down, Sherlock was getting John to help him through the facts.

"So we fell through a wall." He certified.

"I never thought I would be agreeing that that happened." John rolled his eyes.

"We fell through, ended up on a mystery platform and got on a train full of wizards."

"Yup."

The train jerked to a halt and the doors of the cabins flew open, the children piling out and onto the new platform. It was dark outside, but that didn't conceal the view of an enormous castle upon the hill to the right. Sherlock and John followed, mixing in between the rest.

"And who might you be?" bellowed a voice that seemed to come from above them.

They froze, turning round slowly and looking up at a wild-haired man twice the since of the normal-man.

"Wonderful." Sherlock breathed out.