This is a potentially humorous 5e encounter, consisting of two combats, that can be dropped into any urban adventure. The adventure is for up to 4 characters, levels 3-5, but can be modified for lower and slightly higher levels. There's something odd with the plumbing, and is the party greedy, charitable, or foolish enough to explore it? The underground storage area is on the old and decomposed side, so the hook (other than the upcoming 5e adventure by Loke that this preview is from) could that a PC or NPC has bought or inherited an urban building that needs some fixing, and the PCs do a little investigating before the cleanup crew arrives.
The preview is from an adventure included in the Loke Battle Mats "RPG Encounter Toolkit" KS, which also includes fold-out maps, random encounter generators, monster cards, and, of course, Loke's battle mats, which are foldout so you can make not only huge dungeons, but also large areas for miniature skirmish games. If you would like an idea of Loke's random encounter generators and fold-out maps (or want a retail copy now), look for their "Untold Encounters" supplement and "Box of Adventure: Valley of Peril" map set. (The physical Valley of Peril also comes with a digital code for digital content.)