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—
"Okay so... Any ideas on how to deal with potential surveillance fairies other than using infrared cameras to notice inconsistencies and invisible fairies and crossing our fingers?" he asks Promise.
"Ask her if she knows any names of fairies who used to be in the court but haven't been seen in a while."
He relays the question, furrowing his eyebrows, then raising them in comprehension halfway through.
"That's the sort of fairy I'd expect to be on surveillance duty. If she can catch one before they report in and it's one of the ones she's got a name for that's that solved. It doesn't cover all the bases but it's better than nothing."
"Oh. That's fair. I mean, I wouldn't call being able to see invisible things nothing but yeah. I wonder if we should provide Verve with some invisible dart things like maybe that glove or something."
"Shouldn't count on her having enough personal space for a glove to go unnoticed. Earbud's another matter, it isn't likely that anyone's going to fondle her ears."
Probably not.
He turns back to Verve: "How much weight can you carry flying? Can you sneak a bag or backpack into the court site without being noticed, assuming there are no surveillance fairies?"
"...securely attached to your legs? And perhaps to your back, between your wings?"
"Do any more questions spring to mind?" he asks Promise. "I think I'm all out."
"The surveillance stuff is relatively small. The traps less so, but they should probably fit in a bag if the straps are long enough and I can secure it behind her lower back, where the wings won't get in the way. It doesn't need to be as big and clunky as what we used to capture Verve was, since it'll be much lower range."
"Okay. So load her up, send her to approach the court from the right angle via the gate there, have her find a good opportunity to suborn Sand and stash the things in case somebody - picks her up or something, notices she's too heavy - yeah, this could work."
"Keep an eye on her—and Sand—constantly, I think. We can sleep in shifts, you, Yellow, and I, so there's always two of us up and the third can be woken up if anything comes up. Signal from the camera and mic will be delayed by half-a-second whenever we don't strictly need that extra half second, and when we do one of us can rescind any orders that might accidentally slip by."
"Nnnot yet. 'Stop, you may breathe, once your stop order is rescinded act in such a way as to minimise or if possible eliminate the risk of anyone finding out about me, this device, or anything else you sincerely judge could be related to your up-to-date best model of my plans, your stop order is rescinded.'"
"Minimise or if possible eliminate isn't great. Elimination, if possible, is minimization; distinguishing the two might let him get creative somehow - going for a long shot on elimination rather than a conservative minimization. And lots of things could be related to his model of your plans."