"Constantinople!" the Doctor exclaimed excitedly as she stepped out of the TARDIS into an alley, the sun shining brightly in the blue sky above. "Capital of the Byzantine Empire! I always know it!"
"So it ain't had its' name changed to Istanbul yet then, eh, Doc?" asked Graham O'Brien as he emerged from the TARDIS behind her, followed by Ryan Sinclair and Yasmin 'Yaz' Khan.
The Doctor licked the index finger of her right hand and held it out in front of her. "Hmm...definitely ninth century AD...so about six hundred years before the Ottoman conquest and change of name, which weren't the first, by the way. I were here when it were called Byzantium!"
"Bet you were right there for that, Doctor?" Ryan asked. "The Ottoman invasion, I mean."
The Doctor nodded. "Right in the thick of it, Ryan. I'm telling you though, it would've been a lot worse if I hadn't managed to see off those Rutans first. Still, nothing to be worried about at the moment...I think." Ryan and Yaz exchanged silent looks, both aware that when the Doctor brought them anywhere, there was rarely nothing to worry about awaiting them...not that they always minded.
As the four of them walked up the alley the TARDIS had materialized in, the sounds of a busy street grew louder, and they soon found them themselves amid throngs of people walking this way and that, while others peered at the goods displayed in stalls from which vendours shouted to entice yet more customers. "Looks like market day," Yaz remarked.
"It's certainly bustling," Graham said.
Yaz eyed the food and gold and silver trinkets and jewelry on sale. "Fancy doing some shopping, Doctor?" she asked, turning to the group leader...to find the Doctor had stopped dead in her tracks, a chilled look on her face as she stared at something ahead of them.
"Doc?" Graham said. "Doctor, what is it?"
Instead of replying, the Doctor walked forward, rapidly, towards a table outside a street tavern where a man sat with a small pile of various items before him, examining what appeared to be a normal - albeit rather old-looking - flask he held in his hands. As the Doctor's shadow fell over him, he lifted his head to squint curiously at her. "Something ails you, my lady?" he asked.
The Doctor stretched out a finger to point at the flask. "Where'd you get that?" Her voice was urgent.
"This?" The man peered at the flask. "Why, it was among the artifacts I purchased earlier today. Some are said to have been held in the imperial vaults for centuries. I am a merchant, you see. I plan on taking these with me into Europe to sell. Items from the exotic east - particularly those of great age - fetch a very good price there. Though I have no idea what could be in this flask. The cork appears to be stuck, I cannot remove it..."
"Don't!" The Doctor almost shouted the word, causing the merchant to flinch, his expression now one of sheer bewilderment.
He was not alone in his feelings either. Graham, Ryan and Yaz were looking at the Doctor with concern now. "Doctor, what's going on?" Ryan asked. "What's so important about that bottle?"