Prologue
A man stood beneath the streetlight. He took a long, shaky breath and pulled out a cigarette. He lit it with a match, which he tossed in the gutter. He smoked for some time before pulling a small vial. He held it up to the light, though the solution inside was clear. He carefully uncorked it and held it up to the light again, the smoke from his cigarette swirling around it. He pulled the cigarette from his mouth and took another shaky breath. He put the vial to his lips.
"What's that?" a voice called from down the street. The man did not make any indication that he had heard. "No!" the voice called out, a little closer this time. The man drank the vial down in one gulp and tossed it into the night. "No!" the voice called again, now running toward him. The man took another drag on his cigarette before doubling over. He fell to his knees as a man in a tweed coat and a bow tie caught him.
"What did you do? What have you done?" the Doctor asked. "I could have stopped it. I was going to stop it. You were going to be ok."
The man shook his head. "No," was all he said.
"It's not too late. I'll find you again, I'll-" the Doctor cut himself off. He could see it was, in fact, too late. The man was gone. He held the body for a moment, head lowered.
He looked up when he heard a sound from a nearby street. "I'm sorry," he told the dead man. "I have to go. I'm sorry." He carefully set the man down on the street. The cigarette fell from his mouth. The Doctor stood and ran off into the darkness, looking back only once.
.
"The Somerton Man," the Doctor explained as he stepped off the TARDIS with Amy and Rory. "Found dead in the middle of the road on Somerton beach."
"And why are we going to see him?" Amy asked.
"Because that's all anyone really knows about him." The Doctor paused and looked at a street sign. "He should be right around here…" the Doctor looked down the road and slumped a little. "We're too late." If he heard the sound of footsteps running off the other direction, he paid them no mind.
The three of them walked over to the man, looking at him. He looked to be in his 50's, slightly red hair that greyed a bit at the temple. He looked peaceful, at least.
"What do you mean, that's all anyone knows about him?" Rory asked.
"He was never identified. His fingerprints and dental records don't match any known person. They never completely confirmed what killed him. Some sort of poison." The Doctor knelt and examined the man's collar. "Even his clothes are a mystery. No labels."
"He must have been some kind of spy," Amy said. "Murdered by another spy."
Rory shook his head. "I think… suicide. The setting just…" he trailed off.
The Doctor finally stood, still looking at the man. "Well, this is one mystery that will remain mysterious. Come along, Ponds."
The three of them walked back toward the TARDIS. They were about to round the corner when the Doctor grunted. His faced contorted and he held both his hands against his head. He leaned against a wall for support.
"Doctor? What happening, are you alright?" Amy stepped forward and put a hand on his arm.
"I'm fine, I'm fine," the Doctor said a moment later. "New memories."
"What do you mean?" Amy asked.
"Someone's mucking about with my personal timeline," the Doctor explained. "That's never good."
"Who is it?"
The Doctor looked back to the man on the ground. "I think it was him."