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—
Blurs it is. The audio's still awkward, and it turns out audio distortion doesn't really work on fairy voices until the point where they're completely incomprehensible—plain speech is just understood—and that's a step too far in Mortal's opinion, they do need to detect if anything weird and not related to the awkward happens..
Man, Thorn is really paranoid, isn't he. Mortal could almost admire him if he wasn't terrible. Orders are belayed as appropriate, and every now and then renewed just to be sure.
"Are you ready? And in the end should we do stopthensayyourname or sayyournamethenstop, do you think? I hope there are enough bullets there... I hope he hasn't thought of a way to circumvent this. Could he have created wards specifically for darts? Could he have found us out?"
"Hasn't had enough time to develop, let alone opportunity to test, novel ward forms. - I think, I think something would have been different by now if he noticed... and I'm leaning stop first, you don't need the 'then' that way."
"Yeah, not to mention that if he has anything he can activate he won't be able to. Stopsayyourname, okay, good, this will have to be our mortal hireling 'cause he has our names but yes okay."
And then, once again, they wait.
"He's onto us. Is he onto us? Verve and Sand aren't acting weird, they've evaded questioning. He's not onto us. Is he?"
"I don't think so. He may take months to show up at this specific court," Promise says levelly. "Especially since your mother isn't at it."
"The worst part is that we can't really—stop. We can't slip, we can barely talk because something might be going on that needs our attention, and this. Is. Booooooring."