Vault of the Subterranean Cartographers

Beneath a collapsed stairwell and a web of dust-choked corridors, the party finds a long-sealed side vault used by generations of dungeon surveyors and treasure-hunters. There are no fresh signs of battle — the place was abandoned, its doors barred against trespass and time. Inside are the kinds of things a mid-level adventuring party might strip from a well-stocked dungeon cache: coinage and trade goods, useful crafting components scavenged from lost expeditions, a handful of reliable consumables, one tidy magic item that had been locked away for safekeeping, and a fragment of a larger map promising more trouble (and reward) deeper in the earth.