She can hopefully get pretty close, since she's invisible right now, and locate the bedroom that Wood described as belonging to his owner. 

Yup, there it is. A two year old is taking a nap in the big bed right now.

Hmm. Can she do other kinds of magic - oh, first, does her mage-sight work through the window and the presumed shields that block scrying...? 

Mage-sight works!

Jisa tries a teeeeeny mage-light in a corner where it won't be visible to the toddler. 

The toddler is fast asleep. The light works!

All right, she can probably do this? She knows the layout of the room now, it'll be dark when she's actually trying it but she just needs mage-sight to locate the amulet. She'll try breaking the necklace first and - hmm, she can't Fetch it out but she can do a tiny Gate and drop it through, rather than trying to float it all the way to the door or something. If she still can't steal it intact even when the owner is asleep, she'll break it and hope it's more unobtrusive when the elemental is far away and also has a temporary set-command not to harm their owner. 

She should explain the plan to Wood. Is Wood still within her Mindspeech range? 

Yes he is.

:Wood, I found it!: 

Jisa starts explaining the plan. She tells Wood that the previous strategy she figured out for this was to do a preventative set-command so Wood won't instinctively harm his owner, which she promises she'll undo as soon as the rescue is finished. It's especially important because Jisa wants to get Wood out without the owner even waking up. She's going to try to steal the amulet rather than break it immediately as her first plan, because breaking it while it's around the owner's neck might wake him and because she wants to study it, but if she can get away with that she promises she'll destroy it as soon as she's had a look. If she can't, she'll destroy it and hope that even if it wakes him, he doesn't have time to do anything; if that happens she'll make Wood invisible and tell him to fly away as fast as possible and meet her back at the orchard. 

Is Wood on board with all of that? 

:If he were dead he also wouldn't wake up: Wood points out.

:Yes, and I know he's horrible and I don't blame you for wanting him dead, but he's got a family too, I don't want them to be collateral damage, and also if people keep dying around here then it's a lot more likely someone will investigate and catch me and I won't be able to keep doing this, right?: 

:I guess:

:All right, I'll plan on doing it as soon as your owner's been asleep for a bit tonight: 

She squints at the angle of the sun; how long does it look like they have left until dark? 

A couple more hours.

All right, she'll slip back and un-invisible herself and wander around the city a bit more, Thoughtsensing extended, mostly so she can spy on any other elementals going home with their owners and then write down where they live for later reference. 

There's somebody auctioning some off over there - he's caught an Earth and an Air and a hybrid he's calling Storm. People are haggling over them.

Jisa is very tempted to try to buy them - except there's no way she has enough money - or to nab the amulets when they're being handed off and thus easier to steal, but she also can't afford to draw too much attention right now, so instead she watches sadly from a distance and then notes whoever ends up buying them and where they take them afterward. 

A magic school representative snaps up the Storm. The Earth and Air are sold for lower prices to separate people, looking desperately at each other while they follow their new owners away.

Jisa watches them go, and then finds a place to hide so she can sniffle and feel miserable and angry and very, very not-good-enough for a little while. And then it's time to stop pitying herself, and check the position of the sun again and where Wood is right now. 

Wood is on his way home with his owner.

Jisa illusions herself again and then lurks and waits. 

Wood goes into the house, at first, and comes out a bit later, to stand by the door.

Sneak sneak sneak, Jisa creeps invisibly up to the window and peeks through, and extends her Thoughtsensing and mage-sight to peek as well. 

Man and wife and four kids piled into the bed. The two year old is sucking his sister's thumb in lieu of his own.

Oh wow that's a crowded bed. Also, awww.

Jisa creeps back around the house, warns Wood, and does the set-commands, both not to harm his owner and also not to obey his owner's orders, just in case she wakes the mage and he tries to make his elemental slave defend him.  

Then she tiptoes back to the window, to stand there fidgeting and wait until her Thoughtsensing tells her they're all deeply asleep. She's going to need to be very careful not to hurt any of the adorable little kids.