"The Skasis Paradigm" The Doctor said. Symbols continued flashing on the big screen and all the computer monitors. "They're trying to crack the Skasis Paradigm"

"The Skasis what?" Sarah Jane asked.

"The God maker. The universal theory. Crack that equation and you've got control of the building blocks of the universe. Time and space and matter, yours to control"

"What, and the kids are like a giant computer?" Rose wondered.

"Yes" Nova nodded. She looked at Rose. "And their learning power is being accelerated by the oil. That oil from the kitchens, it works as a, as a conducting agent. Makes the kids cleverer"  

Rose's eyes widened. "But that oil's on the chips. Tate and I've been eating them"

"What's fifty nine times thirty five?"

"Two thousand and sixty five. Oh, my God"

"But why use children? Can't they use adults?" Sarah Jane asked.

" No, it's got to be children" The Doctor said. "The God maker needs imagination to crack it. They're not just using the children's brains to break the code, they're using their souls"

Finch entered the room. "Let the lesson begin" He said. Everyone's attention turned towards Finch. "Think of it, Doctor and Nightingale. With the Paradigm solved, reality becomes clay in our hands. We can shape the universe and improve it"

Nova rolled her eyes, while The Doctor put his hands on his hips. "Oh yeah?" The Doctor said. "The whole of creation with the face of Mister Finch? Call me old fashioned, but I like things as they are"

"I do too" Nova agreed.

"You both act like such a radical, and yet all you want to do is preserve the old order? Think of the changes that could be made if this power was used for good" Finch tried to tempt.

"What?" The Doctor scoffed. "By someone like you?"

"No, someone like you. The Paradigm gives us power, but you could give us wisdom. Become a God at my side. Imagine what you could do. Think of the civilisations you could save. Perganon, Assinta. Your own people, Doctor, standing tall. The Time Lords reborn" 

Finch looked at Nova. "I offer you the same, Nightingale, but there is something else you seek. The whole fate of the universe depends on it. Something about stones and keeping them out of the wrong hands. I could bring them to you. You could end the long search"

"Don't listen to him!" Sarah Jane said. "Neither of you!"

"And you," Finch moved towards Sarah Jane. "Could be with him throughout eternity. Young, fresh, never wither, never age, never die. Their lives are so fleeting. So many goodbyes" Finch looked to The Doctor. "How lonely you must be, Doctor. Join us" Finch then looked to Nova. "You too, Nightingale. I can make it certain that you complete your task. You find the stones." Finch then looked between the two Time Lords. "I can also make sure that you two stay together forever"

"I could save everyone" The Doctor said.

"Yes"

"I could stop the war"

"The stones would finally be found" Nova spoke up. "I wouldn't have to search anymore" Then she glanced over at The Doctor, who was staring back at her intently. The two of them joined hands. "We'd be together"

"Forever"

Finch smiled, thinking that he got to them. Sarah Jane began to protest. "No. The universe has to move forward. Pain and loss, they define us as much as happiness or love. Whether it's a world, or a relationship, everything has its time. And everything ends"

The Doctor let go of Nova's hand. He grabbed a chair and threw it at the big screen, breaking it in the process. All the monitors turned off. "Out!" 

______

The Doctor, Nova, Rose and Sarah Jane met Tate and Mickey at the end of a staircase. "What is going on?" Mickey asked.

The Krillitanes began to approaching. They all ran for safety until the came to the cafeteria. There was a door on the other side, but it was locked. Finch caught up to them, followed by all the other bats. "Are they my teachers?" asked Kenny, who was taking refuge in the cafeteria.

"Yeah" The Doctor confirmed. "Sorry"

"We need the Doctor and the Nightingale alive" Finch commanded. The Doctor protectively stepped in front of Nova.  "As for the others? You can feast" The Krillitanes swooped down at all the companions. They hid under a table. The Doctor grabbed a chair and started swinging it at the swooping bats. Suddenly, a laser beam hit one of the Krillitanes. K9 had come to the rescue.

"K9" Sarah Jane cheered.

"Suggest you engage running mode, mistress" K9 said. 

"Come on!" The Doctor called out, taking a hold of Nova's hand. Everyone began running. "K9, hold them back!"

"Affirmative, master" K9 started firing more lasers. "Maximum defence mode"

______

The Tardis team found refuge in the physics classroom. The Doctor shut the door and then locked it with his sonic screwdriver. They were safe for now and finally had the chance to calm down. "It's the oil" The Doctor said. "Krillitane life forms can't handle the oil. That's it! They've changed their physiology so often, even their own oil is toxic to them. How much was there in the kitchens?"

"Barrels of it" Rose answered.

The Krillitanes started battering at the door. "Okay, we need to get to the kitchens. Mickey"

"What now?" Mickey wondered. "Hold the coats?"

The Doctor ignored him and continued to give him direction. " Get all the children unplugged and out of the school. Now then, bats, bats, bats. How do we fight bats?" Kenny set off the fire alarm. All the Krillitanes screeched in pain. That gave everyone a chance to escape.

______

When they got to the corridor just outside the cafeteria, K9 came out. "Master"

"Come on, boy!" The Doctor said. He gave K9 a pat on the head. "Good boy" K9 followed with them. They made it to the kitchen. The Doctor and Nova tried their sonic screwdrivers on all the barrels. "They've been deadlock sealed"

Nova groaned in frustration. "Finch must've done that. We can't open them"

"The vats would not withstand a direct hit from my laser, but my batteries are failing" K9 said.

"Right. Everyone out the back door. K9, stay with me" Everyone except for The Doctor and Nova ran out of the kitchen. "K9, stay with us"

While The Doctor stayed with K9, Nova wheeled all the barrels over in a line for K9 to shoot at. "Capacity for only one shot, Mistress. For maximum impact, I must be stationed directly beside the vat"

"But you'll be trapped inside" Nova said running back over to The Doctor and K9.

"That is correct"

"We can't let you do that" The Doctor said.

"No alternative possible, Master"

"Goodbye, old friend"

"Goodbye, Master"

"Goodbye, K9" 

"Goodbye, Mistress"

The Doctor and Nova both said, "You good dog"

"Affirmative" K9 twitched his antennae and wagged his tail.

______

The Doctor and Nova ran outside. Sarah Jane was waiting for them right outside the door. The Doctor sealed the door. "Where's K9?" Sarah Jane asked.

"We need to run!" Nova told her.

"Where is he?" Nova grabbed Sarah Jane. The three of them ran away from the door. "What have you two done!"

They ran to safety just in time just as the school blew up. All the children and rejoiced as they threw their papers up in the air. One of the students hugged Mickey. Rose and Tate hugged each other. An amused smile appeared on Nova's face when she heard one of the students say, "Oh my God. Kenny blew up the school! It was Kenny!"

All the students began chanting Kenny's name. The Doctor and Nova looked at Sarah Jane. She wore a sad expression. "I'm sorry" The Doctor apologized.

"Me too" Nova said.

"It's all right" Sarah Jane tried to convince herself. "He was just a daft metal dog. It's fine, really" She burst into tears. The Doctor brought her into a side hug, and Nova rubbed her back.

______

The Tardis had relocated itself from the school to Belle Vue Park. Sarah Jane walked up to it. The Doctor and Nova stepped out. "Cup of tea?" The Doctor offered. "Nova made some. She makes a pretty good cup of tea"

"The trick is only a pinch of sugar and a drizzle of honey" Nova said.

Sarah Jane nodded at them. The Doctor and Nova stepped aside so she could step into the Tardis. Mickey, Rose, and Tate were already inside. The Doctor and Nova followed in after her. Sarah Jane looked around and then she looked at The Doctor. "You've redecorated"

"Do you like it?" The Doctor asked.

"Oh, I, I do. Yeah. I preferred it as it was, but er, yeah. It'll do"

"I love it" Rose said with a smile.

"Me too" Tate nodded in agreement.

"Makes me curious to see your Tardis, Nova. Tate mentioned you travel in an old Volkswagen" Sarah Jane said.

"Yep" Nova said popping the 'p' "A Tardis you can both fly and drive"

"Nova's Tardis is lovely as well" Rose mentioned.

Sarah Jane nodded at Rose. "Hey, you what's forty seven times three hundred and sixty nine?"

"No idea" Rose shook her head. "It's gone now. The oil's faded" She looked to Tate for an answer. "What about you? You figure it out?"

"It's faded for me too" Tate said.

"But both of you are still clever" Sarah Jane complimented. "More than a match for them" Sarah Jane nodded towards The Doctor and Nova.

"You and me both" Rose said. She looked towards The Doctor. "Doctor?"

"Er, we're about to head off, but you could come with us" The Doctor offered.

Sarah Jane looked between everyone. She smiled and her shoulders dropped with a sigh. "No. I can't do this anymore. Besides, I've got a much bigger adventure ahead. Time I stopped waiting for you and found a life of my own"

"Can I come?" Mickey asked. "Not with you" He pointed at Sarah Jane. He then looked at The Doctor. "I mean with you? Because I'm not the tin dog, and I want to see what's out there"

"Oh, go on, Doctor" Sarah Jane urged. "Sarah Jane Smith, a Mickey Smith. You need a Smith on board"

"Okay then, I could do with a laugh" The Doctor said. Mickey grinned. "Nova, what do you think?"

Nova grew a huge smile. "Welcome aboard, Mickey Smith!" She shook Mickey's hand. "Believe me, you're gonna have so much fun!" Maybe Mickey was wrong. Nova wouldn't be all that bad to be around. 

"I'm glad you're sticking around, Mickey" Tate said.

"Thanks" Mickey said. He looked to Rose. "Rose, is that okay?"

Rose honestly didn't want Mickey coming along, but she wasn't going to say that to his face. Instead, she said, "No, great. Why not?"

An awkward silence came about. Rose kept her arms crossed as she looked down at the floor. Everyone else glanced at each other. Sarah Jane broke the silence. "I'd better go" She pulled Rose off to the side.

"What do I do?" Rose glanced at The Doctor. "Do I stay with him?"

"Yes. Some things are worth getting your heart broken for" Sarah Jane said. She hugged Rose. "Find me, if you need to, one day. Find me. And tell Tate the same. If he needs to, he can find me" She let go of Rose and walked out of the Tardis. The Doctor stepped out with her. "It's daft, but I haven't ever thanked you for that time. And like I said, I wouldn't have missed it for the world"

"Something to tell the grandkids" The Doctor said.

"Oh, I think it'll be someone else's grandkids now" 

"Right. Yes, sorry. I didn't get a chance to ask. You haven't? There hasn't been anyone? You know?"

"Well, there was this one guy. I travelled with him for a while, but he was a tough act to follow" Sarah Jane smiled and her mind wandered to Nova. "Don't ever let Nova go, Doctor. You two need each other"

The Doctor smiled. "I don't think I could let her go. Not now. Not after I've..." He trailed off, but Sarah Jane knew what he was trying to say.

"She feels the same as you do, Doctor. I can see it in the way she looks at you" Sarah Jane paused. "Goodbye, Doctor"

"Oh, it's not goodbye"

"Do say it. Please. This time. Say it"

"Goodbye, my Sarah Jane" The Doctor lifted Sarah Jane off the ground in a big hug. He put her down and they gave each other a smile. The Doctor walked back into the Tardis. Sarah Jane began walking away as the Tardis dematerialised. At the last moment, she turned around.

"K9!" 

"Mistress" K9 said. He moved towards Sarah Jane.

Sarah Jane kneeled down and pat him "But you were blown up"

"The Master rebuilt me. My systems are much improved with new undetectable hyperlink facilities"

"Oh, he replaced you with a brand new model"

"Affirmative"

"Yeah, he does that. Come on, you. Home. We've got work to do"

"Affirmative"