Flume Fires turns a piece of Otari's lumber infrastructure into an encounter map. A narrow timber flume runs through forested ground, carrying water and logs along a constrained channel with only limited space beside it. The long linear layout is immediately different from a normal clearing: movement is channeled along the structure, the surrounding woods provide concealment, and anything burning or blocking the flume threatens more than the characters standing beside it.

In Troubles in Otari, the flume is important to the town's logging operation and becomes a target for sabotage. For a GM, that creates easy objectives beyond simply defeating enemies: protect the structure, stop a fire from spreading, reach a damaged section, or catch saboteurs before they escape into the trees. The map also works outside the adventure as an aqueduct, irrigation channel, mill race, log slide, or industrial forest route. Its narrow proportions make pursuit and positioning matter, especially when characters cannot simply fan out around the threat.