A small snatch from the the Second Doctor's Yeti era, with still-only-a-colonel Lethbridge-Stewart.
"What do you mean, you've lost them?" the Doctor's tone was light, but there was a fierceness in his blue eyes that gave even the hard-boiled Colonel Lethbridge-Stewart pause.
"I meant exactly what I said," he replied, his spine ramrod straight. "They were here and now they're gone. I have no idea where nor how to find them."
"I only left them here because you promised that you and your men were capable of keeping them safe!"
"And it appears they had other ideas; that young man is very headstrong. My men tell me he tricked them into thinking he was being compliant, then at the first opportunity he and the young lady slipped out. Now…those Yeti creatures…" Lethbridge-Stewart put in hesitantly.
"Are still at large, yes," the Doctor said. He rocked on his heels, rubbing his chin thoughtfully. "But not out in among the general public…yet."
"Do you think they would've gone down into the Underground, knowing those things were down there?" the Colonel wondered, tapping a pen on the table.
"It's possible…" the Doctor said. "But, what's this?" He suddenly reached down and plucked a note from the Colonel's desk-blotter, rapidly unfolding it.
Lethbridge-Stewart frowned. "Doctor…"
The Doctor looked thoughtful. "Gone for vital equipment?" He waved the note at the Colonel. "Why didn't you mention this?"
The Colonel clasped his hands behind his back to keep himself from taking a grab at it. "I didn't see it. Did they leave a note, then?"
The Doctor gave him a look of annoyance. "It didn't occur to you that a note attached to the blotter, and by means of a Victorian hat-pin, I might add, would have come from Miss Waterfield?"
The Colonel took in a breath and let it out again as he gathered patience. "We were searching outside. Does it say where they've gone, then?"
"No. Only that they've gone for vital equipment." He tapped the folded note thoughtfully and sat down in the Colonel's chair. "Hm. Quite an puzzle, isn't it? I wonder what they were thinking of? Why, any number of things might be considered vital depending on your definition of vitality and what it is intended to equip…"
"Doctor! You have no idea where they are, then. Very well. We're going to be starting evacuation procedures for the city, and unless you can make some guesses, we'll never find them until…"
"Doctor! You're back!" a familiar voice called from the hall. They all turned to see Jamie, a smiling Victoria right behind him.
"Jamie! Victoria! Where were you? Why didn't you stay here?" the Doctor demanded, his relief evident in spite of his stern tone, now that he knew his young companions were out of harm's way.
"Oh, well…" Jamie hesitated.
"It's all my fault," Victoria admitted, blushing. "Please don't blame poor Jamie."
"Your fault? What do you mean?" the Colonel asked.
"The lass was that hungry," Jamie began. "An' she said…"
"We just went to the shop down the street," the girl interrupted apologetically. "And I'm ever so sorry we broke your lock. But look, we did bring you something back."
The Doctor suddenly turned all smiles. "Look Colonel! Sandwiches!"
The Colonel rolled his eyes. "London is under attack by hostile mythological creatures, your own companions are blatantly disregarding your instructions and all you can say is sandwiches?"
The Doctor stuffed one in his mouth and smiled. "Believe me, Colonel, when you've seen as much as I have, you'll come to recognize that these," he held up another white triangle of bread, "are vital. One of the most important things in the known universe. Nothing sets right the balance of good and evil quicker than a good tea with sandwiches."
He handed one to Jamie and gave Victoria a little pat on the shoulders. "Thank you, my dear. Well done. Yes, very well done indeed.