For a few moments the size of the inside of the TARDIS didn't dawn on Harry for a moment. The chill had worked its way in here too, but what Harry had thought would be a cramped space for five turned out to be spacious and when he glanced back he found himself standing near the door of an immense room.

Hermione and Ron had already fanned out from the door and were taking the room in. The ceiling was like a bubbled up dome and there was a short walkway that led to a metal grated floor where a circular control panel stood dominating the center of the room. Stairs led down on the other side of the room to an area below the panel. And in the very center of the panel jutting up into the air was a glass tube.

"Blimey," Ron muttered.

The walls were covered with dim lights and there was a door leading to somewhere else. Harry stepped out taking it all in as he headed toward the room's center. The Doctor walked back to lean against the panel. "Surprised? It's…"

"…bigger on the inside," Ginny finished his sentence. "We've seen something like this," she added.

"Mum and dad used to do a trick like this on cars to fit us all inside," Ron said.

The Doctor scoffed. "Magic I suppose. This is simple science—well not simple, but Time Lord technology."

Hermione studied the room, running her hand over the control panel as she passed. "There's more TARDIS ships out there—they're all like this?"

"There was once thousands upon thousands, now this is the last of its kind," the Doctor said. "Even if I wanted to grow more, they take hundreds of years to mature…"

Ron gasped. "Grow? This thing is alive?"

The Doctor nodded.

"There's another door back here—there's more room to this place?" asked Ginny.

"Got everything you'd need for a long trip; library, pool and a wardrobe—there might even be parts I haven't found yet," the Doctor said.

Something outside brushed against the wall of the TARDIS and everyone turned, startled. "The Dementors. They're…running from something," Harry said.

"What could scare a Dementor?" asked Ron.

"I don't know," Harry said.

"Dementors? That's what you call them—they're a bit of a hard case. Couldn't see them myself until I used an old trick," the Doctor delved his hand deep into his pocket, deeper than it should have been able to do and pulled out a pair of flimsy looking paper glasses with one red lens and one blue one. He slipped them over his face.

Ginny stifled a snicker, the Dementors effects seem lessened in the TARDIS. "Remind you of someone?" she asked looking to the others.

"Luna," Hermione answered with a smirk.

Harry walked back to the door and peeked out, the murky shadows of the creatures as they ripped through the street with their ragged cloaks could still be seen. They still moved by, seemingly endless now.

"We need to do something," Harry said.

Hermione shook her head. "No one Harry, no one could cast a Patronus of this magnitude, they could be overrunning the whole city," she said.

Harry slammed the door shut. "We can't just let them devour all of London!"

"Excuse me?" the Doctor said. "Devour?"

"They eat…happiness," said Ginny her face twisting into a worried expression. "And sometimes, they eat human souls…"

There was a lull in conversation and the sound outside became more apparent, the dry rattle of so many death-like creatures. The Doctor ran to the stairs, frantic. "I need you, bushy-haired-pretty-girl…um Hermione…how does this magic you're using work?"

"It's a trait you're born with, though you're lineage doesn't seem to make you more or less powerful…" she paused. "After a while you need to hone it and you need to usually study a lot to do so…"

"This Patronus thing is a type of magic? It gets rid of these Dementors?" asked the Doctor.

Ron nodded. "Yeah," he said.

Below the grated floor the Doctor delved into a closet pulling out all manner of strange devices and items. Ginny followed him down to the lower level. "What are you looking for?" she asked.

"Not exactly sure yet…just planning, looking as I plan," the Doctor said as his hand came out of the closet clasped around a whip. He looked it over. "That doesn't seem appropriate," he said pressing it back into Ginny's hands.

Hermione and Ron clambered over to the edge of the upper level to look down. "Not sure how knowing about magic is going to help you," Hermione said. "You can't use it…"

"I didn't think I could," said the Doctor. "But now then, the wands…tell me about the wands…"

"They're built around cores and we use them to focus and direct spells…" Hermione said. "Magic without a wand is just clumsy and…"

"Direct spells, that's what I thought," the Doctor said cutting her off. He emerged from the closet with a bundle of wires with clips hanging off of them, like multiple jumper cables. He slung the bundle of wires back over his shoulder and headed for the stairs. Before he reached them he grasped the whip in Ginny's hands. "Let's put that back now," he tossed it into the darkened closet. "I need your help with something, everyone over here!"

He led them back to the center of the room where he ripped the control panel open and dug into the wires there. "What are you doing?" Harry asked.

"Saving the city, well you're going to do it…not me," the Doctor said. He tossed the bundle of jumper-cable-like wires over Ron's head. "You, Donald…"

"Ron!" Ron cut the Doctor off.

"Right, Ron—same firs letter as red—pass these out—help everyone get them attached to their wands. Hermione, climb up there and fetch me that single flimsy tubey-thingy," the Doctor said.

"Tubey-thingy?" Ginny cried as Ron helped her attach the clips to her wand. "You don't know the names of things in your own ship?"

"Tubey-thingy, blue-boringers, mallet, and this is how we manipulate the timey-wimey stuff. Okay," the Doctor pointed to all of these things in turn and clapped at the end. "Everyone got their wands hooked up?"

"Merlin's beard…we're all going to die," whined Ron as he nodded.

"We're not going to die," the Doctor said. "Now, Miss Ginny and Miss Hermione—I need one of you to threw this lever when I say go and the other needs to crank that silver thing while pounding on the black panel with the mallet," while he talked the Doctor was using the sonic screwdriver on some wires.

Ginny sighed. "We really doing this?"

Harry looked toward the door, the shadows passing the window of the TARDIS were apparent. "It's all we can do," he said.

"Alright, you ready?" the Doctor asked looking around. "When I give the signal I need everyone to cast that Patronus spell," he said.

They nodded.

"Miss Hermione and Miss Ginny, now please," the Doctor said.

They did as instructed and the TARDIS was jostled to life, steam and sparks raining down upon them as the whole thing shook. "We're only going to have one chance, make it count!" the Doctor shouted.