Unterm Birnbaum is a novella written in 1885 by Theodor Fontane. It is a crime story in which the reader knows from the outset who commits a murder and why. While the details of the murder event itself remain mysterious, the narrative focuses on what others think happened, how a small town's community opinion vacillates over time, and how the community's opinions affect the perpetrators. The reader cannot easily predict whether the murderers will ever be caught.