When the city’s sewers were last expanded, the workers accidentally broke into a vault and discovered a life-sized young dragon made of crystal sitting, ominously motionless, in the center of the vault. The workers immediately plugged the hole and told nobody of what they found (none of the workers wanted to deal with all the questions that would be asked and the likely interruption to their work).
But a few days ago, an old storm mage named Davin Thundergale reopened the vault, after overhearing one of the workers in a tavern talking drunkenly about the crystallized dragon they found. Davin believes that the statue is actually a real blue dragon named Kodax that was crystallized through magic, and seeks to free it in return for knowledge about storm spells.
Davin fancies himself a one-man adventuring party, though he brings with him about a dozen bodyguards, researchers, and cooks. Those are “just his attendants,” though, so they “don’t count.” One bodyguard is an animal tamer who uses several giant fire beetles as scouts.
As a friendly faction, Davin needs a variety of spell components to complete a ritual that will de-crystallize the dragon (an excellent task for the PCs). He’s confident that the ritual will also bind the dragon temporarily, long enough to negotiate with it and keep it from lashing out.
Once all the spell components have been acquired, Davin will welcome the PCs to watch the ritual as it’s performed. The actual outcome of the ritual is up to you. Perhaps it won’t go quite as well as Davin expects.
As a foe faction, Davin worships dragons, and wishes to free Kodax so Davin can serve as Kodax’s highest-ranking follower. His party is a group of rough-and-tumble ne’er-do-wells who follow him for the money, and don’t realize that Davin plans to offer them to Kodax as the dragon’s first meal.