The plan is refined and strengthened, contingencies are set to deal with various ways Thorn could've strengthened his defences, Mortal receives a very interesting email concerning one of their mother's contingency plans—namely that her assets have all been either frozen or transferred to Mortal themself, so Thorn doesn't have access to them -, and when Mortal and Promise judge there's nothing more to be gained from further planning they (eat dinner, sleep again, have breakfast, go over the plan once more when it's not completely fresh in their minds so they see if they come up with anything new, purchase Promise a mobile phone and a power generator to charge its battery in fairyland, eat lunch while Mortal teaches Promise how to use that, and) part ways.
On this side of the veil, Mortal gets to work. The first step: getting at least two safe houses, one for their HQ and the other for contact with the place near Thorn's court. They end up getting five, for redundancy's sake. The main HQ is near Seattle, the other four safe houses are in Greece, Russia, Japan, and Argentina. That, and getting the necessary existing equipment, is the easy part—you end up with contacts of the relevant sort when the bulk of your wealth comes from the kind of thing you can get with sorcery. The hard part is getting the various specific bits of technology that don't exist yet, including the the many types of trap and ammunition they'll need. Processing fairy voices with software turns out to be a dead end—apparently they're weird magical superpositions of sounds that make software go ?!?!?!?!?—but everything else, as agreed upon, can be made to spec nicely enough.
It'll take a couple of weeks beyond the one month for everything to be ready. Mortal hires someone who talks very fast.
And after the ball's going, there's not actually much for them to do with their time. They fret about details of the plan, order more redundant pieces of stuff (especially the to-spec stuff, not being mass-produced means they'd better have a lot of it to start with in case anything goes wrong), and have various antsy and anxious and calm and relaxed and terrified and panicked moods. A month is a long time...
At one point it occurs to Mortal that Promise might've decided to run away and not help, and then they'd never see her again and that would be terrible, and why would it be terrible anyway? It's just some fairy, fairies are evil, one must remember that. Even though she wasn't, of course, she was smart and resourceful and moral and ridiculously hot, and if they never see her again she'll never order them again and the tingly feelings won't ever happen again. Except what the heck, what are they even thinking? The answer, of course, is that they want to see Promise again. Why? To save their mother, of course. The only reason being ordered like that felt good was because Science. Of course. Of course.
The month passes—
"Mirror has all the names except Treecreeper's and Rainfall's, Patch has all the names except Mirror's and Rainfall's, Harp and Songstress and Delight all have different sets of names but I don't know whose because I've received identical orders regarding obeying them and they wouldn't be allowed to enforce on me outside an emergency. Rainfall has Mirror and Treecreeper's names but not Patch's and probably not all the others but likely some of them. It's routine to be commanded to produce truth about the circumstances of one's loyalty and uncompromised status, especially when Thorn's around, and our self-incapacitating contingency orders are renewed regularly. There may be fairies I don't know about stationed in the site for surveillance."
"And the last thing was patterns of movement, what can you tell me about those?"
"There's a lot of time spent on garden maintenance and that accounts for most time spent outdoors by court members. Deciduous and Trance sometimes go out foraging and Songstress is occasionally a scout, solo, she's very fast. Rainfall monopolizes a lot of Windy's time when he can get away with it, which is usually."
And now, for the million-dollar questions: "Does Thorn have a room for himself there, and if so who else has access to it or uses it?"
"Jackpot," he whispers to Promise. "How often do they clean it? How often does Thorn visit? Can you get away with spending some time alone with Sand without drawing suspicion?"
"Would you need that even to spend, say, five minutes with him? Does he spend any time unsupervised? Can you make gates?"
"You can turn things invisible, right?" Then he turns to Promise. "I'm thinking we use Sand to trap Thorn's room. Verve doing something unprecedented would be a security hazard, but I'm not sure there's any way to do this that isn't one..."
"Do you actually think you can tell Sand what you have to tell him in five minutes?" Promise asks.
"No, I'd just need him to grab one of the invisible earbuds and cameras so I could tell him everything while he did whatever else he'd need to do."
"Realistically you'll need some feedback from Sand to confirm details, hard to do if he's simultaneously gardening with someone."
"Yeah, but I was thinking it might be easier to get that feedback during the in-between moments when he's not supervised rather than all at once. Except if he spends most of his time with Eveningstar..."
"Why does he spend most of his time with Eveningstar, ask her that."
"Well, then Eveningstar will definitely be alarmed and probably report it if Sand gets called away and acts at all off even if she's imagining it," Promise says, "especially if she thinks Verve's stealing him."
"It seems... like the best way to deal might still be to get Sand the invisible earbuds and then not order him at all until Thorn's about to come and then have him set up the traps then."
"We'll order him about them, of course. I just mean, in addition to just covering for the existence of the earbuds, he doesn't need to strictly know anything about the plan until he actually has to set the traps. An alternative is, of course, finding a way to trap the entire court and capturing everyone in it. Or capturing Mirror and Rainfall, that should be enough."
"Rainfall - I wouldn't want his attention until we've won. He's good, he's really good. Mirror I don't know."