Holmes and Watson are on their way back to Baker Street from a freshly wrapped-up case when they hear shrieking from around the corner, and naturally they charge around the corner to see what's happening. What's happening turns out to be a giant snake with a mirror for a face. They get the woman it has cornered out of the way, and Watson goes for his revolver, but before he can bring the snake down it gets its face over both of them and they're somewhere else.
"We're from London, in England, on the planet Earth."
"We were not made by that fascinating process that produced yourself just now; we were born, spent time as children, and grew into adults."
He is not giving this talk to a total stranger who came into existence less than two minutes ago. "I don't know how much of the world you're aware of yet, but it seems a fair amount. Are you familiar with animals, and how they bear young?"
"Biologically speaking, yes, but we are also reasoning creatures. I take it your people are unable to propagate themselves in that manner and instead use the mechanism we just saw?"
"You've mastered interplanetary travel, then? Back home it's still in the realm of fantastical literature."
"It's thousands of miles to our moon, and we can't build anywhere near that tall. What do you mean by sails? Between the Earth and other bodies is an airless void; do your sails catch the luminiferous ether?"
"No. We were born, as we said. It is only that things here are very different from where we come from. Now, how do people here get from one planet to another?"
Watson looks at Holmes as if to say, Is she quite sane? Holmes smiles and says, "Fascinating. I would love to see a demonstration."
She blinks at them, then shrugs and turns to the other two and talks to them in their language, then turns back and says, "There isn't a sail in town at the moment, and even if there were, it's not something they want to do just to demonstrate to - you." Maybe they said something less polite than a pronoun that she's rendering that way.
"Oh, if it's not a routine matter we don't want to put you to the trouble. Anyway, it's more urgent to discuss either returning us to where we came from or, if that is as infeasible as it seems, we would appreciate advice on obtaining lodging and employment."
"I am a consulting detective; people come to me with mysteries to solve or strange occurrences to explain and I investigate them. Watson here is a medical man and also helps in my investigations."
"Eminently reasonable. How does one go about doing that? Also, you are currently the only person with whom we share a language. Can we prevail upon you to teach us the lingua franca of the nearest city?"
"Capital! We are ready to set off whenever you are."