John Watson didn't tell no lies to Holmes when he came asking about the glass bottle. He told him he didn't purchase one last night. Wasn't one word of a lie in that. He just neglected to mention the near-full one the red-haired girl left to him. The more time passes, the more that feels worse than lying ever could have. He didn't want that bottle, that's why he put it away with the horse medicines, but this morning he didn't admit to it. He still don't want it. He don't want anything to do with it. A con job, like all the rest, river water and gin. One of these sellers he came across once was telling fat old ladies they could slim down and selling them vinegar to shrink their stomachs. A con job. He ought not have held back.

The boy that cleans out the stalls was late again this morning. Nothing strange there. He's always slept late and he's always got a story to the contrary. John likes listening to it, if he's honest, finds it amusing generally. This morning, not so much.

The kid's old man has been laid up years now with a raw and painful skin complaint. This morning, after liberal application of that slick sliver water, this morning was the first time he woke up with new, hardening skin, not seeping. And though John declared this tale to be the same as the stuff the boy was shovelling out of the stalls, the kid insisted, and told it in such a way that it had to be believed. And then Holmes arrived and… And the rest is a known thing.

But he should have never let himself be took in.

Come lunch, he takes up the cane, puts the bottle in his pocket and starts across town. Holmes wants a sample, he can have one. Sure as hell John ain't going to be putting it to any use, no, sir, so somebody might as well have it.

It ain't the pain of the old wound that bothers him. Pain's a thing a body can get himself past. The longer it goes on, the less it means. The pain ain't the problem, it's the buckling. It's the damned cane, and the struggle, the unpredictability of when it's going to go from underneath him and if there's going to be anybody around to see. But ain't no water in a bottle going to change that and so he's giving it up. Otherwise it'll sit on that shelf until it makes a fool of him.

He takes his time climbing the outside stairs to Holmes' rooms. He has to. But it lets him hear, too, what's going on upstairs. For instance, he must have just missed the slamming of the door, because the shouting now sounds like only the very beginnings of an argument.

"Never ask me to lie like that again!"

Sounds like Miss Hooper from the saloon, that voice. Couldn't be, just couldn't.

"Who asked you to lie? All I said was go up there and get him to sell-"

"-Making stuff up, trying not to condemn myself, what would your brother say if he thought-?"

"Ain't a card you want to try and play, Miss Hooper."

So it is her. And from the sound of things, they ain't got no purpose for what's in John's pocket any more than John does. A disappointment, certainly. But now that he's reached the top of these stairs he ain't much liking the idea of going back down them, and doesn't it anyway sound like the poor girl might be in need of some support? John raises the head of the cane and raps on the door anyway.

Nobody hears him at first. Busy, amongst themselves, with calls and mutterings, "Try and not move them, would you?" and "You want to tell me what I was up there suffering that man for?", more and so on and so forth until John tucks the cane under his arm and knocks hard with his fist instead. Heaven help the neighbour downstairs.

"Hellfire, who's that gonna be right now?!" Holmes throws the door open, "Mind your o- oh. It's you. Come inside. Miss Hooper, John Watson. John, this is Miss Molly Hooper."

"We've met," John says, and only briefly tips his hat to the young lady trying so hard to hide her fluster in new company.

Holmes pauses a moment, perplexed. Then it comes back to him, "Oh, 'cause you drink."

Distant and distracted, quick, cutting, hard to believe this is the same man stopped by the stables the other night. He doesn't even know he's being rude, or that Hooper cried out in indignation, or that there's anybody else in the room or that there might have been some reason John came here. This last doesn't so much as occur to him, having as he does his own use for his presence. "You talk to everybody," he says. "Hear everything, between where you work and the saloon. You know them all. Now what have you heard about the effects of-" And yes, what he produces now is a full new bottle that Miss Hooper must have procured for the effort. John pats his pocket down flat to makes sure it makes no noise and don't bulge too much.

While he's here, he might as well do what he can. He tells what the stable boy told him, about the skin condition, and a story he overheard as he came this way about Mrs Anderson's sickly, invalid son who got up out of his bed today for the first in weeks.

"That's the second story that's come about lethargies vanishing. And the skin, the healing of skin…" Holmes paces, scratching his unshaven chin. There's an answer. His expression makes painfully clear, there's an answer and he can all but reach it. It's distance is murderous to him.

"Symptoms," says Hooper. Small and quiet, but enough to draw attention and make both of them look at her. On instinct she drops her gaze to her own twisting hands. "You called them effects. Ought to call them symptoms."

Holmes is just beginning to roll his eyes. An admonishing look from Watson stops him. Instead, "Yes, yes, you're quite right. Have to remember it's any adverse effects we're looking for."

"No," and now Hooper's voice is stronger, demanding to be listened to, "No, I mean… I know, or… Or anyway, I think I do, know what the cause is."

But there she stops, and with his breath held, with the electric vibration of a child waiting for Christmas, Holmes waits all of four seconds before, "Well?" Still Looking down, shaking her head, she raises up on hand, asking for just a moment to think but, "Not wishing to be indelicate, Miss Hooper, but this is a serious matter-"

"Oh, I know." Her gravity is appropriate, and speaks of a great burden upon her held in high regard. "I know that, and before I send a man to prison, Mr Holmes, or worse-"

"Worse," he nods. She doesn't like his smile. "Definitely worse."

"-Then I should like to be sure, sir, and make a test." Now, as timid as she may be, Miss Hooper stands and straightens down her skirts. She steels herself with a deep breath and goes entirely unbidden to the miniscule kitchen. There's one small square table pushed up against the wall, and this she drags to the middle of the floor and begins to clear it of its messes, reaching for a cloth to wipe it with. "I require muriatic acid," she says with absolute assurance, "and a thin piece of copper."

Holmes and Watson, having followed her this far, can only glance at each other. Then, with a slight raising of his brow and no more, Holmes rolls back around the doorway and goes out of the room. He comes back with a small stoppered bottle of smoked glass, marked with a bright clear warning label, and puts it down on the corner of the table. Most unconvincingly, "Cleaning lady left it."

John, for his part, reaches into his waistcoat pocket and is able to produce a small dome of copper with a lipped edge. "Use 'em for covering the heads of studs," he is saying, as Holmes shows it to Hooper. She very slightly shakes her head and he raises one finger to indicate he has an idea. As he's leaving the room again, for lack of anything else to do, John goes on, "It's fancy-work for people can't afford silver fixings. Keeps its colour longer too, copper, see, so-"

He stops, flinching, interrupted by a sudden and protracted series of shuddering bangs, and when the downstairs neighbour has done knocking on the ceiling with a broom, Holmes is back with a much flatter and thinner piece of metal. "That'll do it," Miss Hooper says. She unbuttons her cuffs. Rolling them back, she seems to freshly notice that they're both still here. By expression alone, she sends them from the room.

Outside the shut door, John whispers, "What's she doing?"

"Seems she knows," Holmes shrugs.

"So what do we do?"

"Seems we wait for her to do it."

There's only that one armchair in the sitting room. Though it's offered to him, John can't take it. Doesn't feel right, when it's so late vacated by Miss Hooper. Besides, his leg is crying out like a spoiled child for the respite and he will not give it the satisfaction. He leans a little heavier on the cane, though, as he rounds the chair towards the window. Holmes breathes out quick for him to be careful, but he's already seen the danger.

The floor behind is covered in playing cards, their intricate backs turned up to the light. It seems nonsensical, and why on earth should Holmes worry if they get moved and shifted out of their straight, precise grid?

But it doesn't take long for Watson to spot it. See, there are plants on the window ledge; a flourishing tomato plant and a few more stunted shrubs, one long stemmed flower that stands up too tall and leans over them all. And all of these things cast strange and unique shadows, cut out harsh by the strong sun, down on the cards. "So that's how they're marked," he muses with a smile. "I'll give you that, Holmes, that is real smart."

"Why, thank you. Ain't often anybody gets to appreciate that."

"Secret's safe with me."

He explains, to pass the time, that this particular window only gets light for a few hours a day, so there's no need to worry about the edges blurring. The sun-bleaching effect around the shadows is subtle, and no uninitiated mind is ever likely to notice when they're only seeing one card at a time. At Hudson's, where Holmes sits in his dark corner, the light comes from behind whatever shill he's skinning and shines through, showing up the memory of the plant shadows.

"But," John adds, "what about these in the top line? Ain't all of them suffering any shadow at all. What do you do about those?"

Another shrug. "Nothing. Keeps things interesting."

"Not interesting enough, though, right?"

"Come again?"

"Well, what do you have to go getting involved in this sort of thing for, if your cards are interesting enough?"

"What's it to do with you?"

"…Ain't, I guess." John considers the cards, slowly learning to deceive, for just a moment longer. Then, with a nod to himself, he picks up his hat and turns towards the door. "You'll excuse me. I'd best get back to my own business."

John Watson goes away with his clear glass bottle still in his pocket and still most of the way full. He's not there when Miss Hooper comes back out of the kitchen, flushed and triumphant with a slight acid burn on the side of her hand. He doesn't hear her tell how she trained to be a nurse, and wound up training under a gentleman who dealt more with the dead than the living. He doesn't hear the words 'forensic' or 'Reinsch test'.

Doesn't hear the words 'arsenic' or 'mercury' either.