Hide it in his bag
It escaped.
Well. The most straightforward way of going about this is to slip into Marshall's tent, leave the package in there, and basically just get it over with quickly.

The two issues with that are, first, Marshall might be in the tent, and second, somebody else might see you. Both of which can be dealt with easily enough as long as you have some plausible excuse for talking to Marshall. You might not be able to plant the package cleanly, but you can at least get away and wait for a better chance.

Of course, the first thing you need is an excuse. The simplest thing that comes to mind is just checking up on all the humans. Nobody would think that was too weird - Starling's already sick, after all. And Rivers, at the very least, would fully expect you to check on her first.

So you head to the tent, and are surprised to find two greblings, with large metal bowls tied to their heads.

"Where's Rivers?" you ask. "I thought she was on watch here."

"She told us she needed a break, and asked us to take over," says one of the greblings. "Um, do you think this is a good enough helmet if Starling tries to get out again?"

You let out a deep sigh.

"I'll just go in and have a talk with her about that," you mutter. You probably need to do this more than you need to deal with Rider's package, anyhow.

When you go inside, Starling is sitting up on her bed. But she doesn't look well at all. She looks worse than she did after Pubert grabbed her.

This probably isn't the time for a lecture after all. You need to give some thought about what to say.
Ask her if she's okay.
She's a little out of it, but she says she needs to tell you something for your ears only.
Do that funny impression that always makes her laugh (on the inside... you think).
"You, uh, you holding up okay, Starling?"

"I'm fine, Boss," she says. She doesn't sound like it at all.

"I'm no doctor, but you're looking in poor shape. You didn't get desert fever in all that mess, did you?"

"No, no, they already checked for that. It's still just swamp sickness, but it's gotten further than usual because they didn't have the right medicine. That's all." She coughs loudly. "The herbalist said I'd probably be fine tomorrow."

She pauses.

"Is anyone around outside?"

"There's greblings keeping an eye on you," you say.

"I'll keep my voice down, then. Come closer - don't worry, you shouldn't catch anything if you put your mask on."

You decide to oblige.

"Do you remember what I said to you in the wagon?"

"Some kind of warning about Butterfly," you say. "She's a spy, you think?"

"Well, it's more than that. I saw her talking to someone, except there didn't seem to be anyone there. But she said something like, she expected a mutiny soon, and there was something about talking to 'the others' before it happened. I wasn't sure what to do, so I went looking for you."

"And you wouldn't even tell Rivers," you say.

"I figured she'd do something reckless. But then, I suppose that's what I ended up doing, and now we're stuck here. Um, I thought maybe I should tell Rider, but I guess I didn't want to do that before checking with you."

"Well, there's not much we can do about it from here," you shrug. "Maybe we'll find a gateway we can use to get back home, though. Then we can deal with it. Assuming the mutiny hasn't already happened."

"Maybe I should have said something sooner," Starling sighs. "I just didn't feel ready for it. With what she said, I wasn't sure who I could trust, except you and Rivers. And Rivers, well. I was worried about what she'd do."

"No point in worrying about it now, it's in the past," you say. "And if we could change the past, well, there probably wouldn't be a lot of Marshguards left."

As you say it, you realize that there's something you've wanted to talk to Starling about for a good while now. And this is your chance.

"Oh, speaking of things that have gone unsaid too long," you add. "One of the Bogknights we caught? He's your cousin. Says he's mad about how his father treated you, back when your parents died. I promised him a chance to talk to you. Of course, if he makes any sort of offer or anything, it's up to you what you do afterwards."

She nods in understanding.

"Jackson, right? I thought he looked familiar. Though, I'm pretty sure I only met him the one time, just before the falling-out between my uncle and my mother, so it's no wonder I couldn't place him."

That raises a few questions, but you're a Marshguard. You don't go prying.

"Well. The way things are going, it might be a while before you can talk to him, if you want to. But at least it's out in the open now."

"Thanks, Boss. I don't know what I'll say to him, but I suppose I'll have some time to think about it."

She smiles, and she's actually looking a little healthier now. But maybe that's just your imagination.

You wonder if you should just stay here and comfort her some more, or if you should get on with your business and finding a way to deal with Rider's stupid secret package.
You don't feel ready to leave just yet. Maybe it's that she's in such bad shape, maybe it's because you're not up to doing secret missions that you can't see any reason to keep secret.

On the other hand, you're not sure where to go from here.

"Is, uh, is there anything you need?" you ask.

"Well, I could use a book or something," she says. "I have a lot of trouble sitting still without anything to keep me occupied. That's, um, kind of what got me running off earlier."

You do still need to have a talk about that, but not until she's better.

"Don't worry about that right now," you say. "I guess you wouldn't have a chance to bring anything, since we left kind of suddenly and you weren't expecting to go at all."

"Yeah. Only what I had in my pouch. But I don't think they want me catching bugs here."

"Probably not. Even if you were up for it, there's always the risk they'd get loose and lay eggs and we'd have an infestation of desert bugs in the swamp."

"That or they just wouldn't do well in all the humidity. Oh, but maybe once I feel better, I can catch some for the greblings to take care of. They probably have an insect specialist."

"It'd make sense, they seem to be studying a lot of different things here."

"I wonder why," Starling muses, and you realize you hadn't given that a lot of thought.

You have a bit of a hunch, though. Not so much about what the point of all the studying is, but why they're out here.

You spent years in a fortress of criminals and exiles. Or, put more simply, outcasts. People who were rejected by their homelands, and had no real place to go.

You can't be surrounded by so many people like that and not recognize the signs here. Greblings here tend to stick to their tents and not come out unless they need something, or Yvonne specifically asks for them. At first you thought they might be wary around humans, but then you realized it was how they acted around each other, too.

Because that's what they're used to. They didn't feel welcome in their colonies, so they didn't venture out much. At some point, the rejection became too much - maybe it turned violent, maybe they just couldn't take the judgmental stares any more. Whatever the reason, this is a place where they can work on their scientific passions in peace.

Or, put more simply. This is their home. And they don't have another one.

"I think most of them study stuff because they like to study it," you settle on saying. "At least, that's the impression I've gotten."

"Makes sense," Starling mutters. She sounds like she's drifting off. A few minutes later, she's snoring loudly.

You can't help but smile at seeing her resting calmly for once. You should find something for her to do when she wakes up.

You head out and tell the greblings she's fallen asleep.

"You sure it's not some kind of trick?" one of them asks.

"She's never been able to fool me," you say. "You can relax."

The guards don't seem entirely reassured, but you did what you could.

So. What are you taking care of next?
We'll better start looking for Marshall...huh, that melody sounds a lot like one you've heard Stings play, never seen an instrument like that before though.
You suppose you should get this package delivered, and to that end, you should figure out where Marshall is.

"Have you seen Marshall, incidentally?" you ask the grebling guards.

"That was the human talking to Rivers earlier, right?"

"Yeah, I think I caught a glimpse of them talking just before we left," you say.

"We took over about ten minutes after that conversation ended. But I couldn't say where either of them went. Might have gone back to their tents, it's getting kind of late after all."

"I guess that's worth checking out. Thanks."

You start heading towards the tent they laid out for Rivers, but then you hear something. Music?

Yeah, that's music all right. Weirdly familiar, at that. Maybe Strings played it once or twice?

You decide to investigate. It seems to be coming from the tent with a holy symbol on it.

Inside is a grebling - you're not sure of his name - playing on what looks like a pipe organ, only much more complicated. There's also an enormous machine, whose purpose you can't even begin to fathom.

The grebling at the organ turns around and glances at you.

"I only do services for Reth," he says. "If you want prayer or guidance on behalf of other gods, you've come to the wrong place."

"No, I was just wondering about the music," you say. "Was that a prayer song you were just playing?" It seems unlikely; Strings never struck you as all that devout.

"Nah," says the grebling. "I was just making sure the pipes were clear."

"What's that song, then? It sounded a little familiar."
The Songbird's Lament.

There's a fable tied to it, something about a songbird being tricked by a crow.

Lots of crow things going on here. Kinda weird.
The same tune is used in other songs. Maybe you recognize it as The Bawdy Cavort of the Krosskan Trollop?
"The Songbird's Lament. Goes with an old grebling folktale about a songbird getting tricked out of a meal by a crow."

"Can't say that sounds familiar," you mutter.

"Well, the melody's not original. It's used for a bunch of human songs, I hear. I think the oldest version was an Aedran war anthem, but after the empire fell the melody got recycled. Probably as a form of mockery. Dunno, I'm not much of a historian, or a musician. Just a simple priest."

You glance at the large machine.

"What's a simple priest need with all that, then?"

"It's supposed to be charting things like air pressure, temperature readings, and just in general information that mostly has to do with the weather. Then I write down the values for our records and clear the charts when they fill up. It hasn't been working right lately. Yvonne was supposed to ask Dominique for the one wrench that works, but I haven't heard anything back about that. Not that I'm surprised."

"It's been kind of a busy day for Yvonne. Busier than she expected," you say.

"Whatever the reason, I don't appreciate being left hanging. Even if I don't have much choice in the matter."

"I could go and remind her," you say. "By the by, have you seen any of the other humans tonight? I'm just doing some checks."

"Only the prisoner. Surprisingly enough, they requested spiritual guidance, and, well, that's supposedly what I'm here for."

Now that has you curious. But it might be rude to press for more information on what happened there.
Pretend to be a priest and go ask the prisoner.
What's so special about that wrench, anyway? Can't you jury rig an acceptable analog out of a pipe or something?
Visits with a priest are supposed to be confidential, and you've had years of suppressing your curiosity when it comes to personal matters. You decide to ask about the other thing that's been bugging you since it was brought up.

"Why do you need a specific wrench? You're out in the desert, it seems reckless to rely on one specific tool. If it goes missing, you'd need to replace it, and that could take weeks. Back in the swamp, we were always improvising when something had to be fixed because we didn't have the right tool."

"I don't know what it's like in the swamp, but my guess would be that you just live there," the priest replies. "We, on the other hand, have all manner of research that depends on precision. If a door falls off its hinges, you might be able to get it back in place with a spear and have it be 'good enough'. But for us, 'good enough' means 'within as small a fraction of a centimeter as we can practically manage'. If our readings are off, then the conclusions we reach by interpreting them will be off."

"Well, I guess that makes sense," you say with a shrug. "But then why do you only have one wrench that good, when more than one of you needs it?"

"Money," he says.

"That makes sense, too," you say. Then you think about it a little harder. "Wait a second, though. Where are you getting any money in the first place? You're in the middle of a desert."

"We get it from people who make money off what we research," he says. "I don't think I'm allowed to say more than that to a stranger."

That sort of answered it, you think. It's probably the best answer you're getting.

Now what?
A stranger? Shoot, you've spent so much time among an insular group of outcasts that you've forgotten about manners. Introduce yourself apologetically and then head out to check with Yvonne about the wrench, keeping an eye out for Marshall along the way.
The word "stranger" stings just a bit. You just barged in here and started asking questions without even giving your name. You're just used to being in a place where everyone either knows your name or doesn't care enough to ask for it.

"Um, sorry for interrupting your practice," you say a little awkwardly. "I'm Corvus."

You extend your hand awkwardly. The priest shakes it, without much enthusiasm.

"Jebediah. Jeb for short. And it's quite all right. I wasn't doing much of anything regardless. Can't really get to work without that wrench."

"I could ask Yvonne about it for you."

"I suppose that's better than having you watch the tent while I do it," Jeb says with a shrug. "May Reth watch over you, honored guest."

You don't think the prayer was insincere, exactly, but he doesn't sound like he cares for giving it.

"Thanks. Er, you too," you say, a little awkwardly.

You head out of the tent and make your way back to Yvonne's. Hopefully Rider won't give you trouble for not making the delivery yet.

On the way, you keep an eye out for Marshall or Rivers, but you don't see either of them. Probably seems worth checking their assigned tents next, but both are a bit out of the way.

You open the flap slightly to announce your arrival, but then you happen to hear a surprising snippet of the conversation inside, and you have to take a moment to think about it.
It is about a ridiculously complicated and irrational conspiracy theory regarding Marshall as the promised savior of the swamp and you should probably just ignore it and grt going
Listen to conversation before you do anything stupid.
"I really don't think relying on a novice wizard for a plan this unlikely is a good idea," you hear Long say.

"Well, I can't manipulate ether myself, so unless you want to end your 'retirement', it's the only option we've got," says Dominique "And you and I both know exactly how hard that would be."

You're getting the distinct impression that Long and Dominique knew each other before this whole desert business. You doubt Long would have explained his situation, whatever it is, to a stranger just because she knows some stuff about ether.

"I have other contacts, you know."

"Well, that's good. And how are you planning on getting any of them here until we figure out how the gateways work? Just hope a gateway opens up in the right place and that we're able to take advantage of it?"

Well, this is sounding complicated. You hope Rider's gift doesn't have anything to do with this mess or you're going to be real annoyed that no one told you what was going on.

"Excuse me," you say. "Um, Jeb says he needs a particular wrench?"

"Oh hells, I completely forgot," Yvonne says. "Dominique, I needed to borrow that from you. But then all this business with kidnappers happened, and..."

"It's okay, I'll take it over to him once this meeting wraps up," Dominique says. She glances your way. "Is that all?"

"Uh, yeah," you say. "Sorry for the interruption. Good luck working this mess out."

You resolve to have a talk with Rider about all this mystery stuff when you get a chance. Assuming he doesn't pull another sudden disappearing act, of course.

You decide that's enough beating around the bush. You may as well check Marshall's tent, and get rid of the damn thing if no one's there, or if Marshall's sound asleep.

At least that's what you're planning, but just as you get close to the tent you hear a loud noise behind you. You quickly turn around and point your mudpike at what might, for all you know, be yet another attacker.

Wait a minute. What in the hells are you seeing?
Dragon? Dragon?!
The lizard worm has its head back at last?
Regardless, nobody can agree on precisely what it is.