A/N: Get ready for one helluva crossover! I have been listening to the "Marshall on Mars" storyline of The Thrilling Adventure Hour, which I highly recommend to anyone with ears and a sense of humor.

Here's their website: Thrillingadventurehour . c o m

Even if you've never heard of this wonderful show, you should have no trouble following this story. I hope you enjoy!

A/N: To guest reviewer Non-eye-mouse: This story does not take place in Knightfury's SH22 universe, though I do love his universe.

I could not quite hold back a sigh. Watson and I had been riding in this tin can of a spaceship (as Lestrade would doubtless call it) for nearly four hours and I dearly wished I could stretch my legs. Or see outside.

But the Yard had granted us use of the cheapest of spaceships, probably to save room in the budget for Chief Inspector Grayson's fooling around with elastomasks and whatever else the man did while supposedly working.

"Only approximately twenty more minutes, dear chap," said Watson in his familiar, only slightly robotic voice. My friend of old was never too skilled at determining distances, but the Yard had installed all sorts of useful applications inside this Watson. If he said twenty minutes, then twenty minutes it would be. It had better not be a moment longer.

A beeping sound caught my ear: my communicator. I answered the call.

"Hello, Lestrade."

"Zed, Holmes, where are you?" she asked, trying to peer around me. She sounded congested, and looked no less ill than she had yesterday.

Watson answered for me. "Approximately fourteen million miles from our destination on Mars."

"Argh!" Lestrade exclaimed. "All it takes is for me to call in sick one day and they're sending you guys to Mars? I can't believe these people." She sighed. "Well, I just wanted to see if you needed my help with anything, but I can't do much when you're halfway across the solar system."

"Technically, that would be much far—"

I elbowed Watson in the midsection to hush him.

"Kind of you," I said to Lestrade, "but I believe we have the situation handled."

"What does Grayson have you doing, anyway?" she asked.

The irritating woman! She ought to be resting. But I supposed that if I did not answer, she would not leave me alone until her curiosity was satisfied.

"Grayson received a request from the United Solar System Alliance to send a detective to Mars. There would seem to be a group of unknown beings gathering all manner of weaponry somewhere on the plains, posing a threat to the Martian tribe and the villagers alike. Some fellow called Captain Caiaphas Nevada requested that Grayson send someone to find them."

"Well, at least it doesn't sound like a hard job," said Lestrade, followed by a sneeze.

"Bless you," I said. "But there is one minor difficulty."

"The beings are invisible," Watson supplied.

Lestrade threw up her arms in despair. "Of course! This would be the job Grayson puts you on! And made you ride half the day in that tin can of a spaceship…oh, that is rich."

"Calm yourself, Lestrade," I said. "I believe we have the situation handled."

"And how is that?" she demanded.

I grinned. "I suppose you'll have to rest up, and I'll tell you at work." I hung up before she could call me any names.

"What is your plan?" asked Watson.

"Well, in my reading, I found that the Martians have a varying number of senses, and I think it is just possible we may be able to find one who can see beings who are invisible to our eyes. Well my eyes, and yo—"

"Technicality," said Watson, waving me off. "They work about the same way."

"Ten minutes till landing," the PA system informed us in a pleasant female voice. "Please keep your seatbelts fastened and your arms and legs away from exits and aisle until further notice."

"I have never been to Mars before," said Watson, apparently by way of conversation. He had been rather cross with me lately, but I had no idea why. If he was out of that mood, I would be glad, even if it meant a little useless talk.

"Neither have I," I replied.

"Is it true that the indigenous people are blue?" asked Watson.

"You are the one with the connection to the Scotland Yard computer database, not me."

"Fair point," Watson replied. "But the connection out here is so spotty I may as well not have it at all. Video and voice calls are about the only data that can be consistently sent and received out here, it would seem."

I only hoped that this would not prove to be a problem.

"Prepare for landing," the PA system said coolly. I closed my eyes and braced myself for one of my least favorite sensations. My stomach had barely been able to stand the takings off and landings of hovercars when I had first come to this century, but ships were dozens of times worse. The little spaceship shook, my insides shook harder, and with a sudden thump we had landed.

Watson and I rose to our seats and crossed to the door. I was already wearing my space suit (part of the reason I was so uncomfortable sitting for hours on end), and when the door opened, we were more than ready to exit.

My eyes adjusted to the light as I descended the stairs to the ground. The sight that greeted my eyes was much like the one I had envisioned the one time I was fool enough to try reading one of Watson's dime novels about the "Wild West": a small village lay before us, little more than a couple dozen squat buildings and dirt roads rested on the flattest ground I had ever seen. The main difference between this scene and the dreadful book was that here the dirt was red.

"The local law enforcement are to meet us here, are they not?" Watson asked.

I was about to reply that I believed so when a dozen women dashed out of one of the nearby houses to meet us. To my surprise, they did not wear space suits. To my even greater surprise, they carried items such as pitch forks, kitchen knives, and nooses.

"Gee whiz!" said a woman in braids. "What're y'all doin' in them there space suit?"

"I have always enjoyed being able to breathe," I replied. "But my friend is not wearing a space suit, as he is a robot. Who is the 'all' to which you refer?"

"All right there, Mr. English Smarty Pants," said woman directly in front of me. She was nearly my height, and gestured wildly with her pitchfork. "In these parts, 'y'all' is a singular pronoun, and 'all y'all' is the plural."

That sounded dreadfully repetitious, but I decided it was in my best interest to remain silent.

"Hey Jane," said a freckled woman in a Stetson.

"Yeah?" the tall woman—Jane—replied.

"Reckon that's enough reason to lynch 'im?"

"I reckon!" another girl replied.

"I wasn't asking you! Gah!" the freckled one replied.

In a moment, all the women were talking over one another, debating our fate. I decided to take advantage of the opportunity to slip off this annoying space suit, if I wasn't going to need it after all.

By the time they determined that I ought to be strung up on the nearest tree and Watson to be dismembered for parts, I had my spacesuit off and an ionizer in each hand aimed at the women.

"All right, ladies," I said in my most authoritative tone. "Show me where the law enforcement is in this town."

"That won't be necessary," said a gravelly voice from behind me. I turned to see a striking gentleman with a gold-star "Marshall" badge. He was muscular and lean, wore a confident grin beneath a Stetson tilted to the side, and was mounted upon what appeared to be a semi-robotic horse. How I wished I could make a deduction or two about him, but I was to unfamiliar with this place to apply any logic to it. "I'm the law in these parts," he said, dismounting his steed. "Sparks Nevada, Marshall on Mars." He held out a hand for me to shake. "And I'm from Earth."

I shook his hand. "Sherlock Holmes, consulting detective. And I am from the nineteenth century."

The Marshall cocked an eyebrow. "Ain't that something? Pleased to meet yah." He turned to the women, now grumbling rather than arguing amongst themselves.

"What have I told you all before about forming angry posses? Insanity Jane?"

The tall woman sighed. "But he's an outsider. Everybody knows yeh don't need a spacesuit in these parts. Not in years!"

Everybody? Wonderful. I would have to thank Grayson personally for informing me of this change in the Martian atmosphere.

The Marshall rolled his eyes. "But that's no excuse for taking the law into your hands. Now scatter yer angry posse."

The group disbanded, though not without considerable sighs of disappointment.

"Marshall Nevada," I said.

"Just Nevada is fine," said he.

"Marshall," I continued, "What do you know about the invisible beings gathering weaponry in this area?"

"That's about all I know," Nevada replied, rubbing the back of his neck with the heel of his hand. "You been sent to help take care of 'em?"

"I have indeed," I replied.

"We have," Watson corrected.

"Ah, excuse me," said Nevada, holding out his hand to my robotic companion. "Sparks Nevada, pleasure to meet you."

"The pleasure is mine," Watson replied. "I have heard a story or two about you."

Nevada grinned. "Good to know tales have made it even to the heart of London."

I took this opportunity to throw my space suit back in the ship. When I returned, the two were discussing some story involving a lasso and a flood. I did not ask for details.

Nevada turned to me. "Now, I'm not used to accepting help from outsiders—"

"Nor am I," I said.

"But seeing as I can't, well, see these invisible beings, I may as well accept any help I can get. We'd best be on our way to tracking them down." At the word tracking, Nevada's face fell.

I wondered at the change, but knew better than to ask.

"I did have an idea about that," I said.

Nevada quirked an eyebrow.

"I am sure you know more about this than I do, but I read that the indigenous people here—the Martians—have a varying number of senses. Might there be one who can see things we cannot, and enlist his or her assistance?"

Nevada frowned and shook his head. "Nah, I think we can handle it all right."

I found that answer lacking in many ways, but uncertain what to do about it, I said nothing.

"Well," said Nevada, shaking off the brooding look, "We best get you two a couple horses to ride, and we'll be on our way."

"We sure will!" came another voice. For a moment, I thought it was Nevada's horse, but was certain I could not be correct.

"Oh yeah," said Nevada. "This is my horse, Mercury. Long story, but there was an alien with a science thing that made all the animals talk and it hasn't worn off yet." He lowered his voice. "I'm just surprised he's been quiet this long."

"Ah," I replied.

"I'm a horse!" Mercury announced with glee.

"Yeah, yeah, they know," said Nevada. "Come on, let's get these guys some horses of their own before they're totally weirded out by this place."

It was rather too late for that, but I decided not to say so. I exchanged a look with Watson which told me he could not agree more.

In less than ten minutes, we had arrived at the local stables, where the freckled woman from the posse granted us use of two horses for the day. I offered to pay—I am still a gentleman, even if I am in a different century and on a different planet—but both the woman and the Marshal just laughed.

"Sorry, Sherlock," he said. "But we ain't all set up to accept credits yet. Folks mostly barter around here, at least until the city council can agree to get the credit transfer equipment installed. O' course, they never do get much done, so it could be years before that happens."

That was rather unfortunate, I thought. Credits were a terribly convenient way to pay for things.

"All right," said Nevada, once we were mounted and ready to go. "Most of the complaints of noises and such have come from west of here, just a few miles from the Martian reservation yonder, so I reckon we better start in that direction." The Marshall nodded towards the setting sun.

"I can detect an excess of radio waves from that way," Watson noted.

I squinted and leaned forward, but could see nothing but the flat, red plains. I wished I had dressed for horseback riding.

"Okay up there?" asked my horse in a strange, throaty tenor.

"I am perfectly well," I replied, trying not to be disconcerted by this. How Lestrade would laugh…

We rode westward for several miles, squinting into the sun and ignoring the horses talking amongst themselves.

From the other side of a large dune came a loud crash followed by muttering in a foreign tongue. We halted. Nevada dismounted his horse. Watson and I followed suit.

"You fellas hide out somewhere. Quitely!" Nevada whispered to the horses. "And if we're not back in ten minutes, go for help."

The horses nodded and sauntered off the other way, miraculously remaining silent. Nevada crept closer to the dune, Watson and I close behind. The voices grew louder and more distinct as we neared it.

"Can you understand them?" I whispered to Watson.

He frowned, adjusted a dial somewhere under his coat, and then nodded.

"It's not a language I'm familiar with, and we are too far from the Yard computers to look it up, but my system can translate it fairly well," he whispered. "They seem to be discussing an object…its shape and purpose. Apparently, it is a 'science gun,' and they need a subject to test it."

Nevada groaned. "Like we need any more of those around here. Maybe they'll find a giant spider to test it on."

"You have giant spiders here too?" I inquired before I could stop myself. Heavens above, whatever would be next?

"Not in this region," Nevada replied. "Thank goodness for that."

There was a burst of light followed by incomprehensible shouting.

Watson's eyebrows shot up. "Apparently, it reverses the relationship between inside and out. We had best be careful; I imagine a shot from that would be fatal."

"Well it ain't fun, that's for certain," Nevada replied. "Unless you've got nanotech—well, never mind, it don't matter."

"You've been turned inside out?" I asked.

"Yeah," Nevada replied. "Strangest, most painful thing I ever experienced. Can't recommend it. The only reason I didn't kick the bucket was Croach and The Red Plains Rider got back in time to turn me back right."

"Who—?" began Watson, but I cut him off.

"Not the time," I hissed, more loudly than I had intended. "Invisible aliens who could possibly turn us inside out. Focus on that."

"Did you just call us aliens?" came a nasal voice from over the dune.

My heart jumped into my throat.

"Because it is rather offensive, you know," the voice continued.

A moment later, we seemed to be swarmed by invisible adversaries. Our hands were secured behind our backs with thick rope, we were relieved of our weapons and carried over the dune into what I presumed to be their camp.

Though our adversaries were invisible, their equipment certainly was not. An array of varying ionizers, lassos, old-fashioned firearms, a small canon, and a whole host of unknown machines met my eyes. Most were gathered in a large pile, but others had been set aside, presumably to be studied or discussed. I wondered which was the "inside-out" gun, and what terrifying purposes the other weapons might have.

We three were dropped with our backs to a rough stone pillar. The beings surrounding us whispered excitedly in their foreign tongue.

"At last!" crowed the nasal voice above the rest, who fell silent. "We have captured the great Sparks Nevada!"

A crow of excitement rose from the crowd.

"And we have captured a robot, whose parts we shall use for repairing our weaponry!"

Another cheer, less triumphant than the first.

"And we have captured…an underfed vagabond!"

This prompted a noise of confusion mixed with vague cheers.

"I am no vagabond," said I, glaring in the direction of the voices. "I am Sherlock Holmes, consulting detective."

There was a pause, then a brief hushed conference was held among the invisibles.

The nasal voice came again at length. "A story about you was assigned in junior high school on our home planet," he said. "But as we are now undergraduate students, we have no time for fairy tales."

"What?" said Nevada. "No, the stories about Sherlock are actually real stories. Like they really happened."

"Oh," said the nasal voice. "We did not pay attention during the Earth literature unit in junior high. It seemed unimportant. Also, should this Sherlock Holmes not be dead?"

"I was, but now I'm not," I said, spitting out some red sand.

"But soon you will be again!"

The cheering commenced once more.

"Nah, we don't give up that easy," said Nevada.

I had to admire the man's confidence; it was rather higher than mine. Perhaps he had another trick up his sleeve. Or was confident the horses had gone for help. Or he was bluffing.

"But you have already lost!" cried the nasal voice.

"Yeah, yeah," said Nevada. "Pretty soon you'll all be under arrest, and there will be quite a pile of paperwork to do after all the havoc you're wreakin' on innocent folk around here. What's the idea, anyway? Invisible aliens, comin' to Mars, just to scare the settlers and Martians? Is that what this is?"

"How little you know!" cried the voice.

"Enlighten us," said I. Stalling for time wasn't the plan I was hoping for, but it was better than being turned inside-out or worse immediately.

"We are not invisible, you fools! Your frail human senses simply cannot detect our presence!"

"Which means you're invisible," said Nevada. "But anyway, what's this about?"

"It is for education!"

"How do you figure that?" asked Nevada.

I noticed then that Watson had been uncharacteristically silent. A swift glance in his direction showed me that he was wearing down the rope binding him on the stone behind us, and Nevada was as well. Unfortunately, I was too far away from it to do so without risking suspicion. Fortunately, I remembered I had a small foldable knife in my back trouser pocket, which I thought I might just be able to reach.

"We are conducting a study on this planet you designate Mars—"

"Because that's what it's called," Nevada broke in.

"—In order to study the culture and weaponry from this region. And then we will do group presentations and receive undergraduate course credit!"

Another cheer erupted. I gave a false sneeze and leaned far enough to the side to reach into my trouser pocket. It was a risky move, but as our adversaries were revealed to be college students, they did not seem quite so threatening as they had before. I managed to retrieve the knife and began to work away at my bonds.

"Well, you could interview us before you destroy us," suggested Watson. "You mentioned culture, and I believe detectives and cowboys would fall into that category."

"Yeah," Marshall Nevada agreed, "That would probably give you more course credit than destroying us."

"On the contrary!" exclaimed the nasal voice. "Cowboys and detectives are Earth culture. We must learn what happens when these weapons are utilized!"

Zed, I thought. How could this get any worse?

"I brought yeh some help!" called a voice from over the rise. It was Mercury, Nevada's horse, and mounted atop him was a gentleman (I use the term loosely) in the black garments of a vicar and holding a what appeared to be a ceramic mug.

"I have some hot cocoa," said the man in a voice as unsteady as he looked. "For it says in the Bible, 'And lo, the day will come when the lawman and two strangers shall be held hostage in a valley by invis'ble aliens, and on that day thou shalt bring hot cocoa to the Marshall and the strangers and the aliens, amen.' And so I have brought hot cocoa!"

In the blink of an eye, the newcomer had been tied up and tossed down next to the rest of us, along with Mercury, whose legs they tied together.

"Hello, Preacher," said Nevada glumly. "Space-crazy as ever, I see." He turned to Mercury. "I gotta admit: you could've done better."

Mercury's eyes widened. "But I'm just a horse!"

"Yeah, okay, I'll let you off the hook this time." Nevada sighed.

Meanwhile, the aliens were passing the mug of hot cocoa around and muttering amongst themselves.

"Man designated as the Preacher!"

"Present," the Preacher replied after a lengthy pause.

"What is this substance? We must deliver some to our professor so that we may receive extra credit!"

"Why," said the Preacher, "that there's just hot cocoa. I got all kinds of it in my house, just for occasions like this."

"Just like this, huh?" Nevada muttered under his breath.

"We will retrieve some from your home. But after we have tested these weapons!"

Nevada spoke up again. "Just go ahead and skip that inside-out gun. I can tell you all about it, so there's no need to shoot it."

"Very well," said the voice, "Let us select another weapon!"

Several gun-shaped objects seemed to rise from the ground as the invisibles examined them, eventually settling on one weapon for each of us.

"Let us begin with Sparks Nevada!" cried the nasal voice. Cheers ensued.

A glance to my left showed me that Watson and Nevada were both free of their bonds. I was nearly through myself. The Preacher would be helpless either way, and Mercury was indeed just a horse.

"You invis'ble aliens won't be beginnin' with nobody!" called a female voice from behind us.

"Step away from the humans!" followed a male voice I did not know.

I craned my neck to see the posse of women who had been so intent on lynching me earlier, led by an insect-like humanoid creature with bright blue skin.

Mutters and a couple screams came from the group of invisibles.

"Croach?" called Nevada. "Is that you?"

The blue man frowned at Nevada. "For failing to recognize me on sight, I place you under small onus."

"I'm just surprised is all," said Nevada. "I thought you'd be, you know, off with The Red Plains Rider, 'cavorting' or some such nonsense. I mean, she did choose you instead of me, and you ran off with her and all…"

"I am Croach the Tracker, not Croach the Cavorter," he replied. "And I have tracked you here to save your life and so reduce my onus." Croach turned to the invisible students. "My senses are far superior to these humans. I can see each of you, and unless you lay down these stolen weapons and depart immediately, I will allow Insanity Jane and her posse to… What is it you do?"

"We'll lynch 'em!" The tall woman crowed. A cheer rose among her companions and they shook their pitchforks with glee.

My ionizer was just out of reach, and I took this opportunity to snatch it up. Watson and Nevada had similar thoughts, and in a moment, we were armed and aiming for the invisibles.

"We are departing! Very much departing!" The nasal voice had a rather panicked ring to it now. Their spaceship was apparently as invisible as they were, but I could hear the clattering of feet as the invisible students rushed on board. "Now we must do our group presentation about Neptune!"

With a loud whirring noise and rush of wind, they were gone.

"All right," called Nevada to Jane and her posse. "You done your part, now go on home."

There were groans all round and several moans of "Aw, no lynchin'?" but the women acquiesced.

For a moment, Nevada and the blue man called Croach stood and stared at one another.

I decided I might do better assisting Watson with the freeing of Mercury and the Preacher than standing too close to those two.

"Oh yeah," said Nevada, turning to me. "This is Croach. He's from Mars."

"G'loot Praktaw," Croach corrected. "Which you designate as Mars."

"It's just Mars," said Nevada. "Anyway, Croach was—well, he used to help me out around here, after I saved his tribe and they granted him to me as repayment of their onus. Croach, this is Sherlock Holmes, the detective, and his friend Watson who's a robot."

"Pleased to meet you," said Croach. He turned to Nevada. "I suppose I will be leaving."

"I suppose you will," said Nevada.

There was another moment of silence.

"You be good to Red," said Nevada.

Croach gave a nod. "Goodbye, Sparks Nevada. I forgive the onus you have incurred by not recognizing me and by my saving your life." He turned to me. "I forgive your onus and that of your robotic companion as well."

"Thank you," said Watson.

"No, don't thank him," Nevada cut in. "That just means more onus, and it really gets confusing."

"It is a small onus," said Croach. "But I will remember it always."

"Yeah, okay," said Nevada. "Bye, Croach."

"Farewell, Robot designated as Watson, Sherlock the Detective, and Sparks Nevada." With that, the blue man remounted his steed and departed in the direction he had come.

"Well," said Nevada, turning to me. "This is a bit of a mess, but I reckon I can take care of it from here. Thanks, Sherlock. It was a pleasure working with you." He held out a hand.

I shook it; he was not entirely a bad fellow.

The ride back to Earth was even less enjoyable than the journey out: this morning, I had not been covered in red sand and I had not been nursing rope burned wrists. I was, at least, able to report to Grayson and Lestrade that our mission had been a success. I opted not to include the details.

Watson turned to me. "Our presence seemed superfluous today. I mean, we didn't really do a whole lot on Mars to justify a nine-hour round trip."

"I can't disagree," I replied dryly. "I wouldn't be surprised if Grayson assigned us this mission just for something to laugh about later."

We sat in silence for a moment.

Watson gave a heavy sigh. "How are we going to tell the Yard that if it weren't for an angry posse of women led by a blue Martian we would have been destroyed by alien college students?"

I laughed. "I have a simple solution, Watson: we will not tell them at all."