From on high he sent fire into my bones

- Lamentations 1:13

Although he'd barely even stopped the car to drop Molly home on the way, it still took John over an hour to get to the address Lestrade had given him, an out-of-the-way flat in Enfield. There was no mistaking it: if the police tape and dozen detectives milling around the front door and step weren't a dead giveaway, the nearby fire engine and the acrid smell blowing all the way down the street was. Getting out of the car at the cross street and hurrying over, John felt a wave of revulsion. Burning human flesh was a smell nobody who had ever experienced it would be likely to forget. He had experienced it before. And he had never forgotten it.

In the days when John had attended crime scenes with Sherlock, the both of them had barged right into the place, usually without stopping to provide ID or even explain who they were—every detective in Scotland Yard had known Sherlock by sight, as had most uniformed officers and SOCOs. This time, however, John told the nearest uniformed officer that Lestrade had summoned him, and waited on the kerb while she went into the house to check that this was the truth. Finally, Lestrade he appeared in the doorway and beckoned him over. John ducked under the police tape and up the front steps to him.

"You really weren't kidding about there being a fire," John said. He was almost overcome by the smell by now, though Lestrade appeared to not notice it at all. Any smoke had been cleared out, for health and safety reasons, but it was protocol that if a victim was found in a room with closed windows, the windows stayed closed until the body could be removed and the room processed.

"Yeah," Lestrade said wryly, beckoning John into a narrow hall. There were five doors off it, three to the right and two to the left, obviously housing individual flats. Further down, in the dark recesses toward the back of the passage, John could see the various detritus of a maintenance crew: a couple of discarded PVC pipes, some scraps of metal, a locked toolbox.

"Let me give you a rundown," Lestrade said, stopping to one side of the door. "Trust me, you won't be paying much attention to me once you go in."

"Victims?" John prompted him.

"Just the one. Her name was Mary Reeser, sixty-seven, widow. One adult son named Richard, who lives in Warrington, married with a wife and four kids. He's been contacted, he's on his way down. The landlady came to Mary's door two hours ago with a letter for her that had ended up in her letterbox in error; she didn't get an answer, tried the door, found it hot to the touch, called us. The local force arrived and realised the door was burning hot and there was a weird smell, so they broke it down and found…" He waved to the door. "There's nothing of her left, John, except half a foot, still in a slipper; her skull; and what I've been told is her backbone."

"Okay," John said, determined not to show any kind of horror about this. "Let's go see."

Mrs. Reeser's front door opened straight onto the sitting room of her one-floor flat, a dated, cluttered little room. The air was thick with heat. In one corner was a deep armchair, upholstered in paisley fabric; in, or rather on, that armchair were what John assumed were the remains of Mary Reeser. At first glance, this seemed to be nothing more than a pile of greasy ashes. As one of the SOCOs moved aside, he caught a glimpse of her foot, or half of it, still clad in a pink slipper.

"'You okay?" Lestrade ventured.

"For God's sake, Greg, I've seen corpses before." John got down on his haunches to examine the remains of the slipper more carefully. It was true; he had seen his share of incinerated corpses. He couldn't remember, though, one who had been almost obliterated by fire, though both he and Lestrade had seen cases where the murderer had had an exaggerated idea of how effective a barrel of petrol and a match would be. Fire was great for destroying evidence, but not so much in the way of destroying a full human body.

"You can see my problem, I suppose," Lestrade said.

John looked around the stifling little room, thinking. "Nothing else is burned," he said.

"I thought the obvious at first," Lestrade said, "she was killed and incinerated elsewhere, and then moved here and propped up, for whatever reason. But Anderson says no; she was definitely burned in that armchair." He pointed at it for emphasis. "Something about the scorch marks on the ceiling and the position of the ashes, or something. I hardly ever know what he's going on about."

John glanced up at the ceiling, reminded of the time he'd come around to Harry's to rescue her from herself and found she'd passed out beside a lit candle, which had left scorch marks up the wallpaper. On the sideboard a few feet away, he spotted a packet of Benson and Hedges cigarettes, only slightly scorched with radiant heat, the gold foil on the outer packet still gleaming. "So she was a smoker," he said.

"Any chance this could have happened if she'd passed out with a cigarette in her mouth?" Lestrade asked him. "Maybe had a seizure, even died like that and dropped it on herself?"

"Doubt it. The human body's mostly water, Greg. It's not easy to burn it to ashes, even in a crematorium." John gingerly leaned over to examine what was left of the woman's corpse again, but could gain no great insight from it. The pink slipper was made of toweling… and toweling was high flammable, he thought. Doctors hated the material with a passion. Almost a year ago, he'd treated a three-year-old whose toweling dressing gown had caught fire from a gas heater and given her second-degree burns to thirty percent of her body. But she had not been burned to ashes. "Who," he said, "would want to burn a woman to death in her armchair? I suppose burning was the cause of death?"

"Impossible to tell now… which might have been the point, come to think of it."

"That's a lot of effort to go to, just to conceal cause of death. Making a suspicious death even more suspicious." John turned his back on the greasy ashes in the armchair and looked about the room. Mrs. Reeser's flat was that of a stereotypical old lady—the kitchen curtains were red gingham and there were assorted photographs of four different teenagers on the mantlepiece, presumably grandchildren.

"So what do you reckon?" Lestrade asked him.

John stood, thinking for a moment. "Dunno."

"Yeah, but you're not wearing your 'dunno' look," Lestrade said. "Out with it."

"Blowtorch."

"Blowtorch?"

"Sure. I assume you could get a fire hot enough to destroy Mrs. Reeser's body like this, but getting it localised to not burn much of anything else in her apartment means it would have to be very hot, very brief, and very contained to a specific area—this chair and everything above it. The only thing that fits that description is a blowtorch." After a pause, "There's some stuff in the hallway, PVC pipes and all that. Were there workmen here fixing the pipes this morning? Would they have used a blowtorch?"

Not for the last time, Sherlock was grateful for a good coat and scarf.

Singapore had been hot and muggy; London was the colour of cold. It was eight o'clock by the time the flight landed and shortly before ten before Sherlock had cleared customs, retrieved the small overnight bag he'd brought with him, and exited the airport.

A cab was out of the question. Anyone would remember a man with such a small bag, but with enough cash on him to pay for a taxi ride from Heathrow to the city. So it was a train, a bus, and another train. Then Sherlock, his overnight bag hauled over his shoulder, walked the last half-kilometre to the end of Station Approach Road.

There was a roof over his head here, but by now it had started to rain, and that rain was coming in at an angle. He looked around in the dull glow of the lights across the street. This place was desolate. Cold, pitiless bricks for walls, and a concrete floor, wet with rain and urine, cracked and worn down with time and care. Every sound echoed here: every drip, every breath.

There were no other living souls around. But there had been, not long ago: the smell was distinctive, the sour stench of unwashed bodies and human suffering.

Laughter suddenly echoed down toward the darker end of the street. Looking up, Sherlock saw two men staggering up the footpath toward him. He knew, or thought he knew, most of the homeless people in London, but these were strangers to him. Both were about his own age, though both looked older on first glance. Sherlock knew how to tell a man's real age by his nasolabial fold. The taller and broader of the two was half-Scottish and came from a broken home with a history of alcohol abuse: he was new in town, but not new to roughing it. The other was a schizophrenic who was on the streets because a female relative—possibly his mother, but more likely his older sister—had just died suddenly, and he'd been set adrift by circumstances.

"Who're you?" He-Who-Was-Adrift asked Sherlock.

"Nobody important," he said automatically. He'd been too dazed, on touchdown at Heathrow, to really think out what he was going to do about his voice; anyone would remember a homeless man with an accent like that. Instinctively, he adopted a more realistic accent for his circumstances, and one that he could imitate well- Lestrade's Londonised West Country burr. He lifted his voice up a touch- the baritone tended to come across as a growl, a threat. "I don't want any trouble," he said mildly. "I'm tired, and just need to crash for a bit."

"Got a smoke?" the half-Scot wanted to know. It was a test, and one Sherlock recognised instantly. Who was he, what sort of a man? A bully? A pushover? A junkie? Did he have anything on him worth stealing?

"Got a match?" he responded. It was the correct answer. Tobacco met fire; the three men smoked in silence for a minute or two. None of them spoke. A grubby, freezing alley was not the place to make friends- it was enough if you didn't make enemies. To this end, Sherlock finally spoke.

"Where do I go?" he asked.

The schizophrenic one pointed. "Down there's where it's warmer," he said. "We were going to start up a fire, but I reckon it's going to be too wet for it. Call you up if there is one, if you want?"

"Thank you."

Stubbing out his cigarette, Sherlock made off in that direction, underneath the arches and between the skip bins from a nearby restaurant. The passage narrowed and gradually dropped below street level; this was a relic from before the trains had come to London. Children had been born and raised in this tunnel. But that had been centuries ago, before the graffiti and the electric lights. It was never made for modern man.

And then, up ahead, something caught Sherlock's eye. He wandered along the dark passageway under the overhead bridge, fumbling with his hands at times, until he reached the spray-painted message on the wall at the far end. Bright pink. Canned spray paint. It shone faintly luminous in the darkness, and proclaimed:

Psalms 142:4.

Sherlock's phone was down to 24% battery capacity, and he didn't know if or when he'd have a chance to recharge it. All the same, this was important. He fumbled to key the reference in.

I looked on my right hand, and beheld, but there was no man that would know me: refuge failed me; no man cared for my soul.

Sherlock was exhausted. He had not slept in three days, and was under the full weight of fear and jetlag. He threw his overnight bag beside the pink writing and dropped down onto the cold concrete. His bag would have to do for a pillow; his coat for a blanket.

Sleep flooded over him like an icy wave.

A/N: On July 1, 1951, 67-year-old Mary Reeser was found incinerated in a chair in her flat in St. Petersburg, Florida. All that remained of her was a shrunken skull, some teeth, and her foot, still in its shoe. To this day the cause of death has been ruled Spontaneous Human Combustion, because nobody can produce a solid theory on how the hell it happened. You can Google both the case and the gruesome crime scene photos.