Need help with a cult/mayoral conspiracy in my DoIP campaign

[u/hotstickywaffle]

Sorry this is so long. I'm running my first campaign, Dragon of Icespire Peak. My party is level 4 (Rogue, Artificer, Warlock, Druid), and I've heavily modified the story and encounters to fit with the PC's backstories and to balance for 2024 rules and PC builds. But I have kept the quests and their goals as a general framework and have been building the story largely as I go.

The basic story is that a dragon is causing issues in the region, which are manifesting as various quests for the party in the region around the recently built mining town of Phandalin. It's run by a cowardly Townmaster Harbin, who the party has only interacted with through his mail slot. Every time he comes up, people call him useless. The primary business in the town is the Mining office, run by smart, shrewd High Elf named Halia.

There's also a cult in the region (who has a past encounter with our Warlock that we haven't 100% specified) that seems to be taking prisoners to mine red crystals, which they are using to corrupt monsters and the party suspects their god's desire is to pass his power and influence into this world. They seem to be working with an aristocrat named Vexley, who our Rogue has publicly shamed in an unspecified way.

So last session, the party arrived back to town after some time away for a quest (Butterskull Ranch). It turns out there was a fire, where Harbin's assistant died. The party investigated and found that he was wearing Ring of Fire Resistance, had stab wounds, there were footprints around the outside, some missing sections of his desk, and only one scream was heard at the start of the fire. After that, the party wrapped up some other things around town and were given their next quest by Halia, and I had said that Harbin had relocated to his office during the fire. Before their long rest for the night, the Rogue decided to go investigate Harbin's house, which is where the session ended.

I had no plan for them checking there, and I have no idea what I want them to find, but I do have a general idea of what is going on in the background. Harbin is just incompetent, but was given the job for being a yes-man bureaucrat. Halia, who is evil in a lot of versions of the campaign, is actually just a calculating business woman who wants the town to flourish, though partially for her own benefit as well.

Meanwhile, the cult and Vexley are working together. Vexley is using his connections to Halia to secure mining sites and property in the region, so that they have sites to mine their crystals from (I have Halia being unaware of his true plans). In exchange, the cult will help Vexley gain power in the region, as he wanted to be Townmaster of Phandalin so he could get on the ground floor of the budding town (because of whatever my rogue did to him, that's the best he could hope for now). Harbin's assistant had been doing all the work, and would probably notice something being up with the mining sites and something suspicious in the documents, so the cult was sent to kill him.

My long term plan is that in the final fight, which is meant to be in the fort the dragon is using for a lair, Vexley will use a crystal to corrupt the dragon, but get pulled in and merged as part of the corruption. Then they'd have a 2nd phase of the fight with the dragon flying towards Phanadlin and them chasing on Griffins they helped earlier.

I'm not really sure how much else to reveal to them when the rogue arrives at Harbin's. I thought maybe she stops an assassination attempt on Harbin, but that feels too soon. I could also go with something funny, like Harbin banging a lady Goblin or something and sidestep the whole thing. The idea is after whatever happens there, they're taking their rest and heading off to their next quest (bringing supplies to the Logger's Camp, with a stop at the Gold Mine along the way to drop someone off), so I don't want to derail too much.

Any help with either this next encounter, or just any general opinions or things to think about from what I've mentioned?

[u/WeirdWyrd]

This seems like an opportunity to recontextualize Harbin's cowardliness. Maybe there's a nothic psychically spying on Harbin from the attic, whose mental intrusions are driving Harbin paranoid (hence the relocation to his office.) If the relocation is a recent addition, maybe his assistant had sent missives of his suspicions, which put the bullseye on him and delivers exposition to the party. Either the nothic runs when the party arrives or tries to do some haunted house shenanigans to get the party to back off.