Inside the Book
It started with a child's nightmares.
Then the child disappeared.
Then the neighbors started dreaming.
The town of Ténébrune has been coming apart for weeks. The first disappearance was easy to explain away. By the fifth, no one in town is sleeping well, and those who dream are beginning to wonder if they'll wake up. The PCs arrive at the request of a friend, or simply pass through at the wrong time. Either way, Ténébrune has a problem that leaves when they do.
The trail leads to a missing apothecary, whose notes reveal a years-long obsession with magical chemicals and a search for something older, something that shouldn't exist in a flask. The PCs follow the clues through town and into the alchemist's home, where the results of that obsession have taken shape: a mindless horror called The Null, born from a chemical wedding of dark magic and alchemy gone wrong.
The Null doesn't want anything. It doesn't plan, doesn't scheme, doesn't negotiate. It simply grows, and everyone in Ténébrune is already inside it.
That Which We Fear is a tight investigation adventure with a clear trail of clues, a contained threat, and a single session runtime. The dread builds slowly before the confrontation, and the horror is in what the alchemist was reaching for, not just what he found.