The Doctor sat on the floor, his back resting against the smooth wall, feeling its coolness through the thin white shirt he now wore. He folded his arms in a vain effort to convey his impatience to Al. That was his name, Al Calavicci. He'd told the Doctor his name to hopefully get some more information out of the Timelord. It hadn't worked.
Now equally impatient and a little worried, Al continued to question the other man.
"I'll ask one more time: what's your name?"
"And I'll ask one more time. Where and when am I? You say that humans have invented time travel? Then that poses a very big problem".
Al seemed to abandon hope of extracting information the normal way. Could it be that for the first time in three years he was going to have to resort to sodium pentathol? He turned around to the door of the room, and was about to shout to Gushie to fetch the chemicals and the syringe. But then he paused. For a reason he couldn't quite understand, he decided to humour the stranger. "And why does that pose a problem?"
"Because humans don't invent time travel until the late thirty-eighth century". The Doctor pointed to Al's cigar, now little more than a withered stump in his hand. "And by then no one, and I mean absolutely no one smokes those".
Al gave his captive a wry smile. "Late thirty-eighth century, huh? Well that's where you're wrong. It's 1998". He turned once again to the door.
The Doctor pushed himself up with his legs, and now stood at his full height. "'1998'? But that's impossible. You don't even have quantum crystals by then. Who on this planet in 1998 could possibly invent time travel?"
Reluctantly Al turned to face the Doctor again. "Maybe you've heard of Doctor Sam Beckett?"
"Sam Beckett", the Doctor repeated. "American physicist, born in 1953, very prominent in all the science magazines until 1995 when he mysteriously disappeared. Is that where he went? Did he travel in time?"
Al saw no point in keeping the truth from the stranger anymore. He'd already told him far more than he had intended, and now that his curiosity seemed to have piqued, he thought he may as well feed the dog another bone and hope for some answers. He folded his arms and began. "Yes. That's right. Doctor Beckett went on a journey in time. He'd been working on a theory for years, and in 1995, he decided to test the machine he'd built on himself".
"So did he go backwards or forwards in time?"
"Backwards. You can't go forwards".
The Doctor sniggered. "Right. Of course. So what year did he end up in? Did he have a knees up with Julius Caesar? Or did he become a knight of the Round Table? No, scratch that, he's American. He went to meet Abraham Lincoln, didn't he?"
Al tried as best as he could to ignore the Doctor's annoying grin. "He can only leap within his own lifetime. He ended up in the fifties".
"And managed to stay out of the history books".
"Course he did. See when he leaps, he has to take the place of someone in history. Just like he's done with you".
"And I suppose no one notices Dr Beckett's arrival?"
"No, never. See, everyone else still sees and hears the person Sam's leapt into".
"So why did he choose to go to the fifties? Did he want to see Elvis live?"
Now Al was definitely irritated. "He didn't have a choice. He never has a choice. He doesn't know where he's going to end up next. He just leaps from person to person, through time, trying to do the right thing, and he doesn't have any damn control over where he ends up next".
Not noticing, or perhaps ignoring that Al was beginning to get upset, the Doctor continued. "So let's get this straight. Sam Beckett invents a machine in 1995 that sends him through time, only within his own lifetime, pulling people to the present as he goes, and he has absolutely no control over where he ends up?"
Al nodded. "Yes".
The Doctor's eyes widened. "See I knew humans couldn't have invented time travel so early! That's not time travel, that's a crude form of time hop scotch! So I take it that Dr Beckett is now in my place?" As Al nodded again, a mask of horror suddenly crept over the Doctor's face. "So he's in the TARDIS. With Amy and Rory. Twenty miles up in orbit around planet earth. Why didn't you tell me? And how could I forget?"
Al was more than slightly relieved that he could now play the role of teacher. "To answer your first question: because I didn't know. That was the information I was trying to get from you. And as to your second question, one of the side effects of leaping is selective amnesia. We call it Swiss-cheesing".
"Like I said, 'crude time hop scotch'. Why do you call it 'Swiss-cheesing' anyway? Is it because it makes your brain hard and go off?"
"No, because Swiss cheese is full of holes. Just like your memory. Now are you going to help me or not?"
But before the Doctor could answer, Al grabbed his shoulder. "Wait a minute! Did you say Sam's in orbit?"