A/N:This story has been reformatted and republished as Chapter 1 of my newest fiction "Explanations", please check that out for all future updates. It can be easily accessed from my author page!

The Eleventh Doctor and Clara Oswin Oswald were travelling in the late 15th Century. They were standing outside the Alcazar Castle in Cordoba, Spain, when Christopher Columbus emerged from the castle a wide grin on his face.

"Thank you, Doctor. For all your knowledge and help. And you Clara, for your bravery and encouragement. I shall repay the favor in kind someday." Columbus nodded and walked off. Clara and the Doctor turned to each other, excited.

"That was Christopher Columbus. The Christopher Columbus. We helped him get to America." Clara jumped up and down with excitement.

"Did someone say Doctor?" River Song strolled around the corner of the building in that moment. The Doctor looked up immediately at the sound of her voice. "Hello, Sweetie."

"River Song." A wide grin broke across the Doctor's face as he embraced his wife, or is she merely an acquaintance. "Where are we?"

"I'm further ahead than you."

"How can you tell?"

"I've met Miss Oswald."

"That'll do it. But any way," the Doctor said as he turned around. "Clara, this is River Song. River Song, Clara Oswald."

"How do you do?" River said as she shook Clara's hand.

"You two know each other?" Clara said looking up at the Doctor's face.

River raised her eyebrows. "We're married."

"Married? You never told me you were married, Doctor."

"It's a long story," he said, look apologetically at River. "I suppose there's a reason you're here?"

"You mentioned Columbus, knew I'd find you here. I did some digging. And I've found something that I think we could help in the early 21st Century."

"What happened?"

"The 4-5-6. Does that ring any bells for you?"

"I've heard of them. I think it was Jack Harkness that mentioned them. He asked me if I knew anything about them which I don't."

"I do. Early Spring 1965," but she paused and looked around. "Probably best if we pop in the TARDIS for a chat actually. I'm thinking 1492 isn't the best time to be talking about events that are going to happen in 1965." She smiled at her husband and at his young companion.

The three of them wandered a few streets over to where the TARDIS was parked and went inside. Clara immediately sat on the bench near the console. The Doctor and River both remained standing near the entrance, though.

"Now. Early spring 1965. The 4-5-6 began broadcasting a message over the airwave with wavelength 456. That's where they got their name. It took most of the spring and summer months for the government agencies of Great Britain to translate, but they did. The 4-5-6 claimed they would release a strain of Spanish influenza capable of wiping out millions of human lives. They would release the anti-virus for a price. The price they requested was 12 children."

"Children? What were they going to do with human children?"

"That's where this gets interesting. In their proposal they stated that the children would not be harmed. That they would live forever. In November of 1965, the government assigned four people the task of escorting twelve orphans who had no one to miss the from the Holly Tree Lodge orphanage in Abroath, Scotland to a designated meeting point. The records showed that the children were to be transferred to another orphanage in Plymouth, but none of them ever arrived and no records were found of any of the children."

"But how does this tie into the 21st Century?"

"I'll get there. It's nice to have a good back story, no?"

"Yes, yes, alright. I'm sorry, dear." The Doctor and River retired to the bench closer the door for River to continue her storytelling.

"The four individuals assigned to the task were: Andrew Staines, a teacher, employed by the orphanage where the children originated; Ellen Hunt, a civil service secretary; Michael Sanders, the man in charge of Britain's clandestine operations at the time; and a name I think you'll recognize, Doctor."

"Who?"

"Captain Jack Harkness. The man that couldn't die was sent to walk the children towards the light beam the 4-5-6 were using to transport them."

"He wouldn't."

"He did," she said look, grievous. "44 years later in 2009 are the events we will prevent the history we can change."

"They came back?"

"For more children. 10% of the world's population of children ages 5 to 11. And the government authorities had every intension of giving them what they asked for until Captain Jack Harkness sacrificed his own grandson to stop them."

"But Jack did it then, why are we going stop him saving the world?"

"We're not. We're going to stop the 4-5-6 from killing about 20 people in Thames House including Jack and his colleague Ianto Jones. We, you and I, have the technology to do what Jack did without sacrificing a human child, especially not his grandson. And I happen to know where they have the station set up we can do it from. We're going to save the day before Jack Harkness has to."

"Alright," the Doctor said turning to the console. "Where to then?"

"Oh, let me, honestly," and River shook her head and pushed her husband out of the way.