A/N: I think this might be my favorite adventure to write yet... Anyway, enjoy! Please review, they make my day! c:

The Devil's Foot: Part One – The Known

Name: The Doctor

Species: Time Lord

Birth Date: Unknown

Planet of Origin: Gallifrey

Known Aliases: John Smith, The Oncoming Storm

Known Forms of Transportation: TARDIS (Time And Relative Dimension In Space), vortex manipulator, "Bessie"

Known Associations: Rose Tyler (see file #254), Martha Jones (see file #298), The Master (see file #301), Donna Noble (see file #342), Harriet Jones (see file #267), Wilfred Mott, Brigadier Lethbridge-Stewart (see file #073), Amy and Rory Williams (see file #421), River Song (see file #500), Sarah Jane Smith (see file #096), Kate Stewart (see file #578)

Suspected Associations: President Richard Nixon, Canton Everett Delaware III, Winston Churchill, Marilyn Monroe, Charles Dickens, J.K. Rowling

Current Whereabouts: Unknown

Latest sighting: Lake Silencio, Utah, 2011, where it is reported that the Doctor met his death

John was browsing through a section of Sherlock's case files which contained a whole cabinet full of folders stolen from the Torchwood archives (not a difficult deduction; there was a line across the top of each file that said Torchwood Archive of Known Extraterrestrial Encounters). This file in particular covered everything Torchwood knew about the Doctor, the last living Time Lord in existence (besides Sherlock, of course). The file detailed all of Torchwood's encounters with the Doctor dating all the way back to Torchwood's origin in 1879, as well as certain events he was known to be connected to: "the Dalek Invasion of 2008", "The Year That Never Was", "The Year of the Slow Invasion," and one particular event known as "Doomsday", for instance.

Evidently, the Doctor had been as vague as Sherlock when it came to the Time War—the only information the file could offer on that particular event was that the Doctor "…also brought an end to the Time War, destroying Gallifrey in the process." Attached to the file, however, were eleven pictures of what John would've assumed were eleven different men. The picture on the top was of a strong-chinned man with a bowtie and side-swept brown hair, which was labeled "Eleventh Regeneration". Underneath was a spikey-haired man in a trench coat labeled "Tenth Regeneration" and they counted backwards from there. He remembered what Sherlock had shown him regarding regeneration and realized with a start that all these pictures were of the same man.

There was nothing else in the file about the Doctor's supposed death. Sherlock still spoke of him as though he were alive—then again, the Doctor was apparently a rather random time-traveller; perhaps he hadn't reached that point yet. Perhaps the event that was in John's past was in the Doctor's future (a conclusion that John was rather proud of himself for reaching without Sherlock's help).

Curious, John sought out the files of all the others. Four were deceased: Sarah Jane Smith, Brigadier Lethbridge-Stewart, Harriet Jones (former Prime Minister), and The Master. Of these, The Master was most intriguing to John. According to his file, he was also a Time Lord, but had been killed during "The Year That Never Was" by his own wife, Lucy. John was most surprised to read that his alias had been Harold Saxon, under which he had achieved the position Prime Minister. No way, thought John, staring at the picture attached to the file. The former Prime Minister had been an alien?

Among the other files, one had had her memory erased and one had been trapped in a parallel universe. Only four were confirmed by their files to be alive and well in this universe: Martha Jones, Kate Stewart, Amy Williams, and Rory Williams. The two latter were married, their addresses enclosed. Martha Jones had separately encountered Torchwood and had, apparently, continued her involvement with the Institute even after her time with the Doctor. Kate Stewart was the head of the science department in the Unified Intelligence Task Force (UNIT for short), taking over after the death of her father, the Brigadier.

That left only two names: Wilfred Mott and River Song. Wilfred, apparently not important enough to include in the archives, didn't have a Torchwood file. River Song's file, however, was perhaps the most intriguing and mysterious of the lot:

Name: River Song

Species: Unknown

Planet of Origin: Unknown

Known Aliases: None

Known Forms of Transportation: Vortex manipulator (?)

Known Associations: The Doctor (see file #001), Amy and Rory Williams (see file #421)

Unproven Associations: The Silence (see file #501)

Current whereabouts: Unknown

Latest sighting: Lake Silencio, Utah, 2011

There was nothing else in her file except for a blurry picture from a security camera depicting a woman with a head of monstrous blond curls sprinting down a sidewalk next to a man John recognized as the Doctor's eleventh regeneration.

Attached to a few of the files were Sherlock's notes on each person—everything from encounters, rumors, sightings, and, most prevalent of all, things he'd learned of them that Torchwood didn't know about. Chief among these things was the casually scribbled note, "The Doctor faked his death at Lake Silencio." Also, on River Song's file, "Sentenced to life in Stormcage prison for the alleged murder of the Doctor," and, "Currently married to the Doctor."

That must be an interesting relationship, John couldn't help thinking.

"John!" came a distant voice.

God, I hope he doesn't ask me to get his pen out of his coat pocket again… "What?"

"Case!"

"Oh, alright," John muttered grouchily, sliding the file folders hastily back into their original order. He got up from the chair he'd been slumped in and headed out down the corridor to the console room.

"Arkansas, 2008," said Sherlock as soon as John entered the room. "Torchwood called about a man who supposedly died of fright inside of his own locked house. There were no signs of a break-in anywhere or anything to suggest who or what could've caused his death."

John's brow furrowed. "Arkansas?"

"Well, yes. Torchwood is worldwide, John. Or did you think it only existed here?"

John supposed, subconsciously, that he did. Most of the cases they'd had on Earth had been based in the United Kingdom. "So they think it might be extraterrestrial then?"

"They aren't sure, that's why they've called me," he answered, punching in a few coordinates and twiddling with a panel of switches on the console. "I don't only solve extraterrestrial cases, John. It just happens to be my specialty." And down went the lever. The workings of the machine pumped and thudded, and John knew they were leaving 221B—and 2012—behind. Or, rather, ahead.

-x-

It was only when John was standing on the victim's doorstep that he realized that at that very instant, somewhere on the other side of the planet, he was stitching up the wounded in Afghanistan. The sudden thought boggled him, and Sherlock was halfway down the front hall before he came back to his senses.

They had parked the TARDIS a little ways down the road, where it disguised itself as a tidy shed with white paint that was peeling slightly. The house in which the victim died was small and ramshackle, with a sagging gutter, a patched roof, and creaky porch steps. There was no garage, but a rusty old SUV was parked in front of the place, looking slightly sad and deject but still plenty sturdy enough to function. The owner seemed to have given an effort to keep a garden some years ago, but it had since been overgrown with weeds. Inside the screen door, it looked about as cared for as the outside. There was a splotch of mildew on the otherwise white ceiling, a table that looked like it'd had its legs chewed on by a dog, a ratty old rug, and two dusty picture frames hanging on the wall—one depicting a middle-aged, doe-eyed woman and the other a scraggly man with a long, thin nose.

"Thank you for coming, Mr. Holmes," said a surly man with a head of thick black hair and a particularly heavy brow. He glanced at John, but if the doctor's presence bothered him, he didn't show it. Sherlock nodded, and the man introduced himself as Don Clarkson before leading them into the sitting room.

The walls of the room were painted an ugly blue, but it was hardly noticeable under the seemingly random assortment of framed pictures, mostly filled with the same two people whose portraits he saw hanging in the front hall. There was also a flat-screen TV of a size highly disproportionate to the state of the house, two arm chairs that looked to have seen better days, a sofa in similar condition, and a rickety coffee table. A door across the room led, apparently, to the kitchen.

The room might've been called homely had it not been for the body resting in one of the arm chairs. It was the scruffy man depicted in the pictures, sitting up in the chair with his rigid fingers still clutched around the arms of it and his expression one of deepest horror. His mouth was twisted into a terrible grimace, his eyes frozen wide and fixed on the doorway through which John and Sherlock had just entered. John faltered, frightened by the dead man's expression but too morbidly intrigued to look away. Sherlock, though he hadn't stopped as John had, was staring at the body with the same blank, faintly surprised expression.

"Freaky, ain't it?" said a voice from the door of the kitchen. "It's had that effect on everyone so far. Like his stare's holding you at the door." John managed to tear his gaze away to look at the speaker, a short, skinny, red-headed woman with a smattering of freckles across her cheeks. "Vanessa, head of Torchwood Eighteen. You already met Don—he's the medical examiner. Can't make heads or tails of it though. No sign of extraterrestrial involvement as far as we can tell, but the victim, George Redstone, was healthy as an ox before he dropped dead. His wife, Martha Redstone, hasn't been found yet—she looks to have vanished."

She seemed to have been directing her conversation at Sherlock, but the Time Lord didn't appear to be listening. John's eyes followed him across the room as he advanced, peering at and around the body. John noted that, for the first time, the detective seemed wary of touching the body. He examined it very closely under his magnifying glass, but not once did his fingers so much as brush its skin or clothing.

"Who found him?" asked John, and the woman, Vanessa, looked at him with mild surprise, as though just noticing him.

"Neighbors said they heard 'terrified screaming,' so they called the police to have a look, and… Well." She paused. "There were two other men with him—friends of his, we assume, probably over for a game of poker or something—who we think witnessed the man's death."

"You think?" repeated John.

"They aren't making any sense, see," she said. "Been driven out of their minds with whatever happened."

John was silent for a moment, taking all this in. "So—what did he die of, exactly?"

"Heart attack, so far as we can tell," she said, scratching the back of her head. "Doesn't make any sense, though. Like I said, he was in perfect health."

It seemed to take John a great effort to bring himself closer to the dead man. He bent over slightly, looking closely at the body as Sherlock had done and trying to ignore the face staring past him. The man didn't appear to have been arranged the way he was sitting; rigor mortis had already set in, and there was no way anyone could've made his face look like that post-mortem—something had to have caused it just before his death. What could have scared a man with no history of heart condition so badly that he'd died of fright? Was it even possible? A person being "scared to death" was only an expression, he'd thought. In all his days in Afghanistan, at least, he'd never seen anything like this—and if he were to see it anywhere, that would be the place.

"What do you think?" muttered Sherlock, examining the man's fingernails.

Mirroring his low voice, John answered, "She seems to be right—it's a heart attack. It looks like something scared him enou—"

"Stick to the facts, John," Sherlock interrupted. "Was the body moved or adjusted post-mortem?"

"No," replied John, holding back an annoyed look.

Sherlock moved on, taking a peek into the kitchen before walking in a slow circle about the room. He looked at the second empty chair, picking something from the fabric with a pair of tweezers and placing it delicately into a small bag; at the remote, which was on the floor by the dead man's chair; at the flat-screen TV; at one of the framed pictures; and, finally, he stopped in the front doorway, his brow furrowing. "John." He beckoned his companion over. "Do you smell that?" he asked as soon as John crossed the room.

John took a few sniffs. "Smells like rotten eggs," he said, all too familiar with the smell after the case of the yellow moon. "Sulfur, you reckon?"

"Sulfur," repeated Sherlock in a murmur, his focus sliding into the distance. "Sulfur…" His eyes were darting back and forth, as if an array of possibilities was laid out before him and he was glancing from one to another, mentally checking each one off. Suddenly, his eyes widened and he gasped, his mouth forming an "O" of comprehension. "Of course—yes, of course…"

Before John could ask what he'd just thought of, Sherlock was back in front of the body, crouching down in front of his face. He came away clutching a swab which he slipped inside of a vial and pocketed as John watched. "We're going," he announced loudly. "I'll call if I find anything promising."

"Not so fast," said a deep, gruff voice from the entrance to the front hall.

John turned. Two men were standing in the doorway, both wearing suits and unsmiling expressions. The one who had spoken—the shorter of the two—stepped forward and both brandished their IDs. "Agents Freeman and Costner, FBI," said the first. He had short brown hair, a strong square jaw, and a critical way of looking them up and down. The other one, who stood several inches taller than Sherlock, had shoulder-length hair and a tight-lipped mouth.

John looked momentarily confused as he glanced at their IDs. Freeman and Costner…? He could've sworn he'd heard the names before…

Sherlock turned to face them, his gaze cool and calculating for the briefest of moments. A second later, he had his phone out and was tapping away at it, sounding bored as he asked, "Why is the Federal Bureau interested in the death of George Redstone?"

"I'm afraid that's below your pay grade," replied the other in a self-satisfied sort of way. "Who are you, anyway?"

"We're Torchwood," said a voice behind them, and John glanced over his shoulder to see Vanessa stalking up to stand beside them. Despite the fact that she was nearly a foot and a half shorter than the second man, her dark eyes, narrowed in suspicion, gave her a rather intimidating countenance. Sherlock looked up. "And our 'pay grade' is high above yours. So talk."

They exchanged a glance. This time, the taller one—"Agent Costner"—spoke: "We received instructions from our superiors to investigate this case. They showed interest in the cause of death and believe it may be related to the recent theft of a high-security biochemical weapon."

John glanced at Sherlock. It would explain quite a lot, but Sherlock's eyes were still narrowed, and he had a slight upturning of the corners of his lips that led John to believe he knew something.

"Well, I'm afraid we don't know any more than you do, agents," said Vanessa, still coolly.

"Agent Freeman" looked pointedly at Sherlock, who still said nothing. "You sure about that?"

"Quite," replied Sherlock, and this time John knew he was hiding something. "I'd like the phone number of your 'superiors,' if you don't mind."

They gazed at each other for a moment, sizing each other up. Finally, the agent pulled out a scrap of paper, scribbled down a number, and handed it to Sherlock, who pocketed it. "John," he said, sweeping past the two agents. John, after a glance at each man, followed.

As soon as they were out of the house and a little ways down the street, John asked, "Okay, what do you know and why didn't you tell those blokes? Obviously they're dicks, but they do have the authority—"

"No they don't. They're not from the FBI."

After a split second of stunned silence, John asked, "How can you tell?"

"Their suits were cheap, and brand new, as if they'd just bought them but didn't want to bother keeping them. I caught a glimpse of the tag in the one man's collar and looked up the name of the brand; it's local, only found in this area of Arkansas. Rather suspicious, don't you think?" Before John could answer, he continued, "And the 'high-security biochemical weapon'? Please. A possibility of terrorism like that would've been a matter of national security. They wouldn't have sent in two berks to have a look, they'd have sent a whole team to confiscate the body and quarantine the house. And of course there was the gun in the one man's holster: a six-shooter, and definitely not government issue by the looks of it." John was about to say something, but Sherlock spoke over him, gesturing over his shoulder, "Then there's their car. An old clunker, well cared-for, but still old—not exactly standard rental, is it? Did you catch a look in the window when you walked by? It's definitely been lived in during the past several years, at least, possibly even their whole lives."

John waited for a moment. "Done?" he asked finally.

"With that, yes. I can't begin to guess what they want or why they're here without more facts, though I wouldn't disregard the possibility that they're involved. It would certainly explain their secrecy."

"Alright, so what about the dead man, George Redstone, then? What could've caused him to 'die of fright'?"

"'Die of fright'?" Sherlock repeated. "John, people don't 'die of fright.' They have heart attacks, they overdose on hallucinatory drugs, they suffer the effects of certain airborne poisons. 'Dying of fright' is just an expression that was used when nobody could explain such things."

"Alright, then, how did he die?" asked John.

"You said it yourself. Heart attack."

"But—"

"Yes, John, I know! I know he's too young and he has no history of heart condition and he was 'healthy as an ox.' I also know that this case seems awfully reminiscent of The Devil's Foot, and—"

"The Devil's Foot?" John repeated. "Isn't that—?"

"A case, yes, from Conan Doyle's books, in which two brothers were driven mad and their sister killed from fear. Sounds a bit like our dead George Redstone and his two mad friends, wouldn't you agree?" There was a certain manic quality to the way Sherlock was speaking. John familiarized it with the detective's incredulity at how unbelievably slow everyone else's minds worked. Before John could interrupt again, he continued quickly, "There is a certain brand of airborne pathogen from the planet Krakatoom that smells of sulfur and causes its victims to hallucinate their worst fears just before their death." As he spoke, he reached into his pocket and withdrew the vial containing the swab he'd used earlier. "I swabbed the victim's nostrils. If he inhaled the poison, I can test this for it to prove it. It's a very rare poison, but it would fit the story of The Devil's Foot."

John's confused expression cleared. "Ah." He glanced over his shoulder, back towards the house. "But what would he—George Redstone, I mean—have to do with it? He seemed like any other bloke to me, no one special. How'd he run into… Krakatoom dust?"

"Exactly," said Sherlock. "We need to talk to his wife."

"I thought they couldn't—"

"—Find his wife? Yes, well, they don't have a TARDIS or a genetic sample of the woman in question." He withdrew a little baggie from his pocket and John saw that there was a single long, blonde hair.

John couldn't help a half-smile at that and neither, apparently, could Sherlock. The Time Lord was at the top of his game now; this was what he lived for, this feeling of a chase—that with every minute they were getting closer. John could see by the look in his eyes every idea that flitted through his brain, saved or discarded as easily as if they were files on a computer.

They reached the TARDIS and pushed through the shabby wooden door into the impossibly enormous interior. Sherlock bounded up to the console and pressed a tiny blue button. A long, narrow glass cylinder rose up from the console's surface and the Time Lord used the tweezers to carefully extract the hair from the bag and lower it into the cylinder. When he released it, it simply hovered there, swirling slightly as if suspended in thick, clear liquid. John watched as he flipped a number of switches, typed a few lines of instructions, and heaved the lever down.

"This will track her genetic signature and take us somewhere within five hundred feet of wherever she is at this exact moment in time," said Sherlock as he watched the ringed pillar of light in the central column slide slowly up and down. "Whether she's dead or alive, I don't know, though personally I think she's alright."

John didn't ask why he thought this, because the TARDIS touched down at that moment. "Where are we?" asked John as Sherlock examined the screen.

"A hotel not far from where we were," he replied carefully, staring at the circular Gallifreyan words written across the screen.

They both turned back to the door, which had shrunk to a size John hadn't thought possible. They could fit through it, yes, but it would take some less-than-graceful maneuvering to do so. "After you," said Sherlock, and John could've sworn he heard smugness in his tone. So, holding back a grumble, he crouched down and pushed outward on the door, clambering out headfirst. Despite his attempted caution, he fell in a sprawling heap to the floor which he identified to be concrete. Sherlock emerged a moment later with a bit more finesse as John was brushing himself off.

They appeared to be in the basement area of the hotel. Huge pipes across the ceiling hummed and trembled, and next to the TARDIS rumbled a few washing machines and dryers. The TARDIS had, apparently, disguised itself as a washer, for John looked back to see the dim light of the cavernous console room shining dully through its open door.

Only when they had both stood up, brushed themselves off, and cast a simultaneous look around for a door did they realize that they weren't alone. A tall, thin woman in a pastel yellow uniform and white apron was clutching a bundle of towels and staring openly at them in shock.

For a moment, they just looked at each other, each party lost for words. Finally, Sherlock spoke, kicking the washer's door shut before she could take notice of it. "Just inspecting your washing machine," he said, brandishing what looked like a simple leather wallet in the same manner as the two FBI agents had showed their IDs. "It's broken. Don't touch it, it could explode." The woman's gaze switched to the wallet, her expression more puzzled than surprised now, but before she could say anything, Sherlock closed it and swept past her.

"What did you show her?" asked John in a low voice as they headed swiftly up the stairs. He found it hard to believe that Sherlock just happened to have a fake washer inspector ID.

"Psychic paper," replied Sherlock, handing the leather wallet to John. "It shows people what they want or expect to see. She probably saw the card of a health inspector."

"It's blank," said John when he'd opened it, revealing a square of plain white paper.

"Yes, well, you seem to have a propensity for seeing past perception filters," said Sherlock, taking the paper back and giving John a brief, searching look, as though hoping to find an explanation tattooed in tiny letters somewhere on his face.

They emerged from the stairwell into a spacious lobby with smooth tile flooring and beige walls that accentuated the bright sunlight very well and created a pleasing effect of openness. The man at the desk, short and portly with a well-trimmed beard, looked up as they entered. "Who're you?" he asked suspiciously, sitting up a little straighter.

"Police," answered Sherlock, pulling his psychic paper back out of his pocket and flashing it at the doorman. "We're looking for Martha Redstone. Can you tell us which—"

"I'm right here," said a soft voice to their right. John and Sherlock looked to see the woman portrayed in the pictures standing just outside of an elevator. She had a slightly worried expression on her face. "What's wrong? Is it something about my husband?"

"Yes, I'm afraid so," said Sherlock, adopting a sympathetic, almost paternal tone of voice. "Your husband… died last night. I'm so sorry…"

"No," she said in a tremulous voice, her wide eyes defensive. "No, you're wrong. He's not—he can't…" But she seemed to read the sincerity in Sherlock's face, and a gasping sound like a wounded animal escaped her throat. Sherlock guided her to an armchair where she collapsed, shaking with sobs, tears streaming down her face. The pair of them waited in uncomfortable silence for several minutes until, finally, she managed to control herself enough to speak. "How—how did he die?"

"Heart attack," answered Sherlock calmly. John was astonished at how quickly and easily he could just slide into the persona of someone who was the opposite of Sherlock Holmes—this comforting figure was very different from the usually inconsiderate man that John had to deal with. Watching him act like this made John wonder whether or not he knew just how much he normally inconvenienced those around him—or did he just not care? Perhaps it was a little of both.

"Heart attack?" repeated Martha shakily, her throat bobbing a few times as she attempted to swallow back more sobs. Her brows had contracted slightly in a strained and confused expression. "B-but he's healthy—I mean, he doesn't work out, but he—he keeps in shape."

"That's why we're looking into the possibility of murder," replied Sherlock. "Do you know anyone who would want to see him dead?"

She shook her head, bewildered. "No, I mean—I don't know… He doesn't have too many friends, but he doesn't have enemies either… We're a very private family, um—what did you say your name was?"

Sherlock didn't answer. "Why were you staying in a hotel?" he asked. "We had a job of finding you."

"We had a fight," she said, and her eyes widened suddenly, her face twisting as she threatened to dissolve into tears once more. "Oh, God—the last thing I said to him—we were so angry with each other…"

Sherlock didn't seem to notice how troubled she was by this realization. "What about you?" he asked, and John heard the return of the sharper tone he usually used for interrogating suspects. "With the way he treated you, surely you would've loved to be free of him, and what better way—"

"How dare you!" she barked, suddenly rising to her feet, blazing anger heating her shining gaze. "I'd never—I didn't want this! I love him!" Suddenly suspicious, she said, "Where are you IDs? Who are you? You have no right—no right—"

Sherlock pulled out his psychic paper, but she was already pushing past them. "I'm going home," she snarled, heading for the door.

They stood there for a moment as the door closed behind her. "That went well," remarked John sarcastically.

"Come on," said Sherlock, ignoring this remark and walking back towards the stairwell. The doorman was glaring at them in a disapproving way, but he didn't say anything.

"What did you mean, 'with the way he treated you'?" asked John as soon as they were out of earshot of the man. "Was she abused?" Sherlock nodded. "How did you know?"

"I don't think he ever beat her," said Sherlock. "I saw no signs on her of bruising or afflicted injury. But he had a temper, most certainly, and she had a tendency for giving in whenever he asked for something. What did you notice about the picture frames, John?"

The question caught him by surprise. "They were all level, but they seemed a bit… random."

"They weren't," replied Sherlock. "They were all at about the same height as my shoulder. One of them had a crack in the wall extending from behind it. I'm almost certain that if we were to lift any one of those frames up, we would find evidence that the wall had been punched there. There was also a profound lack of ceramic or glass in the house, other than the windows—all the dishes in the kitchen were plastic, and there weren't any vases or ornate pottery to be found, probably because if there were, he'd grab them and throw them across the room. Then there's the TV," he added as they reached the washing machine that the TARDIS was so cunningly disguised as. The startled maid was nowhere in sight. "Rather expensive-looking, wouldn't you agree, when the rest of the house is so disheveled?" Without waiting for John to agree, he opened the door to the washing machine and continued speaking in a louder tone so John could hear him as he wriggled his way inside. "Likely she bought it as a way to make him happier. He probably hinted something along the lines that he would love her more if she bought it for him."

"So, you think the wife did it?" asked John as he made his way inside after his friend.

"No, definitely not," replied Sherlock. "Whatever he did to her, she was devoted to him. Didn't you notice how she refused to adopt past-tense speech throughout the entire conversation? Anyway, she wasn't living in constant fear of him—you heard what she said. They had a fight, and she left to stay at a hotel for a night. It was probably a common occurrence, more common than it would be in a better relationship, but it shows she could've left if she wanted to." He was adjusting the controls to the TARDIS now, piloting them who-knows-where. "It could've been one of her friends, perhaps someone who'd noticed their dysfunctional lifestyle and thought they were doing her a favor, I suppose."

"Where are we going, then?" asked John.

"Right now, nowhere," replied Sherlock, reaching into his coat pocket and once again pulling out the vial containing the tiny swab. "I want to test this first. If this was the cause of death, then it'll prove which case this is, and I'll have an idea of where to look for the killer."

"According to the books, you mean," said John. Sherlock nodded. The Time Lord pressed the same small blue button he'd pressed earlier, and the same narrow glass cylinder extended from the console. He deposited the swab inside the cylinder, where it hovered, and typed a long line of instructions. When he pressed enter, a thin line of red light ran up and down the cylinder like a barcode scanner. Then a few flashing red Gallifreyan symbols showed up on the screen, and John could tell by Sherlock's confused face that this wasn't at all what he was expecting.

"It tested negative," the detective muttered, more to himself than anyone else. "It wasn't the poison that killed him."

John voiced the obvious question hanging over both of their heads: "Then what was it?"