This is a dungeon crawl designed for a single evening of Dungeons & Dragons.
 
Long has the farming district of Lhanwold toiled under the shadow of nearby Silvervale. The former is a key crop exporter in the region and supported by the salt of the earth; the latter is in possession of a silver mine and has grown languid as a result of being able to create new currency on a whim. For years this had gone on without much ado, as both cultures were content in their existence. One month ago, one of the gleaming city’s ambitious princes returned from a diplomatic mission over the neighboring mountain range which serves as a boundary between nations. He has established an arrangement with that foreign land to import crops through Silvervale, who will then sell to this region at a profitable markup which still manages to undercut Lhanwold’s prices.
 
This sparked a minor revolt which then escalated into a minor war. Lhanwold has marched on Silvervale, who in response activated an artifact buried deep under the city called the Reflectrix. Now, a massive impermeable dome of shimmering energy encases the metropolis, bringing the siege to standstill. Lhanwold’s civilian militia stands within a stone’s throw of Silvervale’s gates, torturously unable to pass through the magical barrier.
 
As it turns out, one of the Lhanwold elders is a Silvervale native, but forsook the city as a young man, abhorring its arrogance and seeking a simpler and more rewarding life. Although that was 70 years ago, he still remembers a rumor: there is a secret tunnel which leads into the city’s crypts…or rather, from them. It was originally dug as an escape route in the event that the city was to be sacked, but after a century or two of peace it was essentially forgotten. He posits that either by hubris or ignorance, the city might not have secured this back door, and so an infiltration might be possible if anyone were bold enough to undertake such a mission. And that is the state of affairs when the party arrives at the outskirts of the Lhanwold crop fields...