The starship Niamh, roughly 60-70 years after it left Earth. It’s now about a light year away so communication is basically impossible with Earth and is no longer attempted. For all intents and purposes the Niamh is a fragile and closed ecosystem. Nothing can leave and nothing can come in.
The vents of the spaceship grow a special kind of mould, which can be extracted in meth-lab like setups to produce a psychoactive euphoric drug. This drug is illegal on board the Niamh but people will still produce it anyway. It’s spread by spores which travel through the ventilation ducts. No matter how much they try, they can’t seem to get rid of the mould. It just keeps coming back.
A segment of the officer and military class is beginning to doubt the success of the mission. Another 700 years on board the ship, their grandchildren’s grandchildren’s grandchildren and so on and so forth. Rebellion is swiftly quashed by the executive branch of the ship.
Meanwhile, the ship’s working class lives a fairly basic existence. They work for 8 hours a day, six days a week, and their bunks are shared with another person who works an opposite shift to them. When A is out, B is in and asleep. A and B rarely, if ever, meet. Particularly downtrodden members of the working class turn to the drug to brighten up their dull existence. But this causes problems as not much work is getting done, and the ship is beginning to suffer as a result. With no ingress or egress of materials and resources, the ship has to run perfectly, else the mission will never succeed.
In the laboratories, scientists have finally produced an antifungal which is 100% effective against the mould. But a rogue element within the science department leaks this information to the working class, and a cell of terrorists determined to keep the control over the working class that they’ve eked out with the drug puts a stop to it.
