Donna walked in with two cups of tea.

"Here we are, Dr. Moon." She said.

Her daughter ran up to her, showing her a clay figure.

"Mummy, I made you!" she told Donna.

"Oh, that's nice, Ella." She said, looking at the doll. "Where's the face?"

"I don't know." Ella replied.

Donna put the cups on the table and looked around at the empty room, confused.

"Did you see Dr. Moon?" she asked. "Did he leave?"

Lee entered the room and the children ran to him.

"Daddy!" the shouted.

"Hey!" he called back. "Hello, you two, come here! Big hugs, big Daddy hugs!"

"Look what I made!" Ella told him, showing him the figure.

"Oh, it's Mummy?" Lee asked.

"Erm, it hasn't got a face." Donna pointed out. "Did you see Dr. Moon?"

"No." Lee replied. "Why, was he here?"

"Yeah, just a second ago." Donna told him. "You must have passed him."

She moved to the window, but instead of Dr. Moon, she saw a veiled woman in a black Victorian dress.

"You all right?" Lee asked, moving behind her.

"Yeah." Donna said. "Yeah, I'm fine, it's just…"

"Just?" Lee prompted.

"Nothing." She said, hugging him. "It's been a long day, that's all. I'm just tired."

Donna was in her pyjamas, in her bedroom with Lee.

"You okay?" he asked.

"I said I was tired, and…" she trailed off, confused, before remembering. "And we put the kids to bed, and we watched television."

They heard a noise from the front door.

"Was that a letter?" Donna asked.

"It's midnight."Lee said.

"Go and see what it is." Donna told him.

Lee left and Donna walked to the window. Outside she saw the same woman in black.

"'The world is wrong'." Lee said as he came back in.

"What?" Donna asked.

She turned and saw Lee holding a letter in his hand.

"For you." He told her. "Weird, though. 'Dear Donna, the world is wrong. Meet me at your usual playpark, two o'clock tomorrow."

Donna took the letter and walked back to the window. Below, the woman was walking away.

In her living room, the girl was scared.

"Don't go." She begged. "Please don't go."

Donna arrived at the playground with her children. A little ways away, she spotted the woman in black, her face hidden behind a veil.

"All right, you two, off you go, no fighting." She said, shooing her children off.

The kids ran off and Donna sat down beside the woman.

"I got your note last night." She told her. "'The world is wrong', what's that mean?"

"No, you didn't." the woman told her.

"I'm sorry, what?" Donna asked.

"You didn't get my note last night." The woman said. "You got it a few seconds ago. Having decided to come, you suddenly found yourself arriving. That is how time progresses here, in the manner of a dream. You've suspected that before, haven't you, Donna Noble?"

"How do you know me?" Donna asked her.

"We met before, in the Library." The woman replied. "You and your red haired friend were kind to me. I hope now to return that kindness."

"Your voice…" Donna whispered. "I recognize it."

"Yes, you do." The woman told her. "I am what is left of Miss Evangelista."

Flashes of Miss Evangelista, alive and dead, suddenly went through Donna's mind.

In the Library, the group ran through a corridor connecting to tall buildings. Suddenly, the Doctor stopped.

"Professor, go ahead, find a safe spot." He said.

"It's a carnivorous swarm in a suit, you can't reason with it." She told him.

"You don't know the Doctor as well as you think, obviously." Luna told her smugly. "If he didn't try once and fail miserably, he wouldn't be the Doctor."

She reached up and kissed his cheek.

"You die, I bring you back and I kill you, understand?" she told him. "I'll keep them safe."

"Understood." He replied. "I thought I'd have to threaten you to leave."

"Truthfully?" she said. "They scare the crap out of me. I rather let you deal with them. Have fun."

"Oh, thanks." He said sarcastically.

"You're welcome." She replied brightly.

"Other Dave, stay with him, pull him out when he's too stupid to live." River ordered. "Two minutes, Doctor."

The rest left just as the thing that used to be Proper Dave arrived.

"Hey! Who turned out the lights?"

The Doctor moved closer to it.

"You hear that?" he asked. "Those words? That is the very last thought of the man who wore that suit before you climbed inside it and stripped his flesh. That's a man's soul trapped inside a neural relay, going round and round forever. Now, if you don't have the decency to let him go, how about this? Use him. Talk to me. It's easy, neural relay. Just point and think. Use him, talk to me."

"Hey! Who turned out the lights?"

"The Vashta Nerada live on all the worlds in this system, but you hunt in forests." The Doctor said. "What are you doing in a library?"

"We should go, Doctor!" Other Dave called.

"In a minute." The Doctor replied. "You came to the Library to hunt, why? Just tell me, why?"

"We…did not." The Vashta Nerada said, using Proper Dave's voice.

"Oh, hello." The Doctor said.

"We did not." The Vashta Nerada repeated.

"Take it easy, you'll get the hang of it." The Doctor told it. "Did not what?"

"We…did not…come…here." It told him.

"Well of course you did." The Doctor replied. "Of course you came here."

"We come from here." The Vashta Nerada told him.

"From here?" the Doctor asked.

"We hatched here." It said.

"But you hatch from trees." The Doctor replied. "From spores in trees."

"These are our forests." It told him.

"You're nowhere near a forest, you're in a library." The Doctor told it. "There are no trees in a…"

He trailed off in realization.

"…library." He finished.

"We should go, Doctor!" Other Dave called again.

"Books." The Doctor marveled. "You came in the books. Microspores in a million, million books."

"We should go, Doctor!" Other Dave repeated.

"Oh, look at that." The Doctor said, looking out at the endless city of books. "The forests of the Vashta Nerada, pulped and printed and bound. A million, million books, hatching shadows."

"We should go, Doctor!" Other Dave repeated.

The Doctor looked back at him, suddenly realizing that wasn't the first or even the second time the man had said that phrase.

"Oh, Dave!" he said sadly. "Oh, Dave, I'm so sorry!"

The lights on Other Dave's neural relay were blinking and behind the helmet was nothing but a skull.

Both skeletons began to move towards the Doctor.

"Hey! Who turned out the lights?"

"We should go, Doctor!"

"Thing about me, I'm stupid." The Doctor told them. "I talk too much, always babbling on, this gob doesn't stop for anything. Not even Luna. Drives her batty. But you wanna know the only reason I'm still alive? Always stay near the door."

He pointed the sonic screwdriver at the floor and dropped through a trap door. He quickly grabbed a beam and began to crawl along it, the screwdriver in his mouth.

The girl watched him, smiling.

"I suggested we meet here because a playground is the easiest place to see it, to see the lie." Miss Evangelista told Donna.

"What lie?" Donna asked.

"The children." She replied. "Look at the children."

"Why do you wear that veil?" Donna demanded. "If I had a face like yours, I wouldn't hide it."

"You remember my face, then?" Miss Evangelista said. "The memories are still there-the Library, the Doctor, me. You've just been programmed not to look."

"Sorry, but…you're dead." Donna told her.

"In a way, we're all dead her, Donna." She replied. "We are the dead of the Library."

"Well, what about the children?" Donna asked. "The children aren't dead. My children aren't dead."

"Your children were never alive." Miss Evangelista told her.

"Don't you say that." Donna told her. "Don't you dare say that about my children!"

"Look at your children." Miss Evangelista told her. "Look at all of them, really look."

Donna finally looked. Everywhere she looked were the children. The same two children. Over and over again.

"They're not real." Miss Evangelista told her. "Do you see it now? They're all the same. All the children of this world, the same boy and the same girl, over and over again."

"Stop it!" Donna ordered. "Just stop it! Why are you doing this? Why are you wearing that veil?"

She reached over and pulled off the veil to reveal a horribly distorted face. Donna and all the children screamed.

The girl screamed and covered her face with a pillow.

In the Library, River was examining the shadows with her screwdriver, while Luna stood by the door, watching for the Doctor.

"You know…it's funny." River said. "I keep wishing the Doctor was here."

"The Doctor is here, isn't he?" Anita asked. "He's coming back, right?"

"You know when you see a photograph of someone you know, but it's from years before you knew them?" River asked her. "It's like they're not quite…finished, they're not done yet. Well…yes, the Doctor's here. Luna made sure he came when I called, just like she always does. But they're not my Doctor and my Luna. Now my Doctor…I've seen whole armies turn and run away. Luna has stood by his side for centuries and has pulled him out of countless dangerous situations and they'd just swagger away back to their TARDIS. He opens the doors with just a click of his fingers. The Doctor... In the TARDIS... His moon following him, protecting him... Next stop: Everywhere."

The Doctor suddenly walked through a different door from the one Luna was keeping watch at.

"Spoilers!" he said. "Nobody can open a TARDIS by snapping their fingers. It doesn't work like that. Well, actually, Lu once managed to open them by saying 'open sasamy' but I'm pretty sure that a bribe exchanged hands."

"It does for the Doctor." River told him.

"I am the Doctor." He shot back.

"Yeah." She replied. "Some day, you might actually be."

"Oh shut it for a second!" Luna shouted, running up to him and jumping into his arms, making sure to wrap her legs around his waist to keep her up before burying her head into the crook of his neck. "I thought you were a goner for a second you idiot! I thought you were gonna be comin' back with a pair of shadows and a swarm of flesh eating parasites in a pinstripe suit!"

"Well, lucky for you, I'm not." he told her, smiling brightly before letting her down.

"Now, how are you doing?" he asked Anita.

"Where's Other Dave?" River asked.

"Not coming." The Doctor replied. "Sorry."

"Well, if they've taken him, why haven't they gotten me yet?" Anita asked.

"I don't know." He told her.

He looked down at her shadows.

"Maybe tinting your visor's making a difference." The Doctor mused.

"It's making a difference alright." She said. "No one's ever going to see my face again."

"Well, they're not exactly missing much Anita, are they?" Luna joked, grinning cheekily.

"Oi!"

"There we go... Humour lightens the situation a little. Now, is there 'ought you can think of? Anything I can get you?"

"An old age would be nice." She replied. "Anything you can do?"

"I'm all over it." The doctor cut in, smiling.

"Doctor…" she said. "When we first met you, you didn't trust Professor Song. And then she whispered a word in your ear, and you did. And then she whispered something to Luna, and she did too with a smile. My life so far…I could do with a word like that. What did she say?"

She paused, waiting for an answer.

"Give a dead girl a break." She finally said. "Your secrets are safe with me."

"Safe…" Luna murmured.

She exchanged a look with the Doctor.

"What?" Anita asked.

"Safe." He repeated. "You don't say saved, nobody says saved, you say safe. The data fragment! What did it say?"

"4,022 people saved." Luna repeated from memory. "No survivors."

"Doctor?" River asked.

"Nobody says saved, nutters say saved"

"The Doctor might slip up and say 'saved'" Lu continued, understanding where he was coming from.

"You say safe." He said. "But you see, it didn't mean safe, it meant…it literally meant…saved!"

"What happened to your face?" Donna asked.

"Transcription errors." Miss Evangelista answered. "Destroyed my face, did wonders for my intellect. I'm a very poor copy of myself."

The girl watched them talking on the television.

"Where are we?" Donna asked. "Why are the children all the same?"

"The same pattern over and over." Miss Evangelista replied. "It saves an awful lot of space."

"Space?" Donna questioned.

The girl was very scared.

"Cyberspace." Miss Evangelista replied.

"No!" the girl shouted. "Don't tell, you mustn't tell!"

"See, there it is, right there!" the Doctor said, pointing at the screen of an information terminal. "A hundred years ago, massive power surge, all the teleports going at once. Soon as the Vashta Nerada hit their hatching cycle, they attack. Someone hits the alarm, the computer tires to teleport everyone out."

"It tried to teleport 4,022 people?" River asked.

"It kinda sorta succeeded." Luna answered. "You've really got to give it points for attempting. That was truly inspired."

"The problem was not getting them." The Doctor explained. "It had them, but it had nowhere to send them. Nowhere safe in the whole Library with Vashta Nerada growing in ever shadow. 4,022 people all beamed up and nowhere to go. They're stuck in the system, waiting to be sent, like emails. So what's a computer to do? What does a computer always do?"

"It saved them." River murmured.

"And it's still doing it!" Lu cried, smiling brightly. "It must be doing it 'cause it's grabbed Donna when we sent her back to the ship. Poor machine, it's still trying to save everyone."

"The Library, a whole world of books, and right at the core, the biggest hard drive in history." The Doctor said. "The index to everything ever written, backup copies of every single book. The computer saved 4,022 people the only way a computer can."

"It saved them to the hard drive." The trio said in astonishment.