D&D 5e - Beneath the Keep

This is a session 0 event to go over future campaign and one off adventures, party mix, character creation, character leveling, magic items, gold, faction (optional), renoun, downtime, etc.. This is not current AL DnD rules, but a lot of the guidelines will be based on old AL DnD season 7 (Forgotten Realm settings) and 2014 characters rules.
If time permits and party agrees I plan to run a short one off adventure.

During a brief stop-over at a wilderness stronghold, a simple trip to a local provisioner reveals foul play! The shop has been broken in, and the shopkeeper is missing—but the place has not been burglarized. The heroes are thrust into an investigation. Clues discovered by the heroes hint at larger corruption that festers among the border lands surrounding the stronghold. What sinister forces lurk beneath the keep?