Quest: The Lost Guard

Adrian Knowles was sent out to begin an apprenticeship under Xerxes in Set'hn and hasn't been heard from since. The party is called by Rane and asked to find and retrieve him.

Structure

Exposition

The party is chilling at the Hekan Guard, things are business as usual. It's early in the evening, and a thunderstorm is rolling over the desert. Thunder booms outside every so often, muffled heavily by the mountain around them. 
Things are quiet until a loud crack of thunder hits overhead. Several minutes later, a hawk flies over the party and they find some HASTILY scribbled, slightly damp notes from rain asking for them to meet him asap.
On the plateau, rain pelting down, stands Rane and Xerxes. They're arguing in hushed tones about Xerxes leaving his post in Set'hn, Rane saying it's dangerous for him to travel this far south, it's VERY quiet and would need a nat 20 to hear probably. Upon noticing the party, Rane introduces Xerxes as his brother and explains their task.
He explains that Xerxes is the head of the Hekan Guard in Sap'meh, posted in Set'hn. One of the members of the guard was transferred north to become his apprentice- a young blue tiefling named Adrian Knowles. Adrian was a member of the guard a few months before the rest of the party joined. Xerxes explains that he believes a beast or bandit group probably grabbed him. He will explain if asked that he hasn't been able to send out the northern guard to find him because they A) have a much smaller amount of members than the main branch and B) have been dealing with their fair share of strange attacks lately. 
The party's task is to track down Adrian and bring him back.

Conflict

A blue dragon named Ozolos, The Stormqueen, Render of the Skies, grabbed Adrian as he was traveling and brought him back into her lair as a plaything for her young wyrmling. He's unhurt, but very scared and unable to leave because of the clingy baby dragon.
Adrian Knowles

Rising Action

The party makes their way north. On the way there, they may encounter some stray undead mummy fucks and some duneskimmers once they hit the border of Sap'Meh. They could also find a band of Kobolds carrying what seems to be some kind of stone obelisk across the sands, which they claim is the symbol of their great god. It's a fucking rock. They could also find Sol, who seems much more reserved and concernced than usual. If pressed, she'll explain that she feels the sun's light growing dimmer.
They can track him in many ways, though the most obvious sign of him would be his camel mount and belongings left behind in the middle of Sap'meh. He had rations, a map, and a bag of 20 ish gold, along with a journal about some of his journeys in the guard and how excited he is to be studying under the great Xerxes. Some of the supplies is burnt, and the sand in the area around it is burnt into these weird branching glass patterns. They may recognize it as lightning- lightning breath from a blue dragon. 
As they search further for him, Ozolos herself may fly overhead, maybe seeing the party. They see her fly off to a nearby rocky plateau where the thickest, darkest stormclouds seem to hover over.
Upon approaching the plateau, they see that it's an almost monolith type rock that's fucking MASSIVE. The ground around it is  If they roll high perception/investigation, they'll be able to find the entrance up around 120 feet in the rock or the entrance burrowed into the ground around the plateau.
Inside the structure is a huge, very vertical cavern that seems to shoot straight up through the plateau. In the bottom is some kind of subterranean lake, the banks of it surrounded by a hoard of odd items and crystals. In the very middle of the lake, about 60 feet out, is a sandy island with a sort of divot in it and walls built up of crystals and coins. High perception checks will show some kind of movement in the center- it's a smallish, blue, scaly shape. In the middle is Adrian. The wyrmling is sleeping, and Adrian is trying very hard to not move. He seems a little bruised and has a nasty bite wound around his middle, but seems otherwise unhurt. The party has to get him without upsetting the baby and before mama can arrive! 
In the lair there are some strange magic trinkets, roughly 5000 gold worth of money if the party is willing to grab it all, several gems, and a few rarer items if they roll well: https://www.dndbeyond.com/magic-items/17451-ring-of-lightning-strikes  https://www.dndbeyond.com/magic-items/5976-bag-of-wondrous-randomization
Ozolos is a calm, cold, calculating dragon. She will taunt the party and try to provoke attacks out of them, but otherwise seems bored with them. She'll eventually attack them if they stay around too long. Her wyrmling is curious and cute, but definitely has a hunting instinct and might hurt the party while playing.