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Erwin Schlumpf, a young ex-convict, is arrested for killing the traveling salesman Wendelin Witschi, who was found shot in the head in the woods near the Bernese village of Gerzenstein. Sergeant Studer makes the arrest, then returns to find Schlumpf hanging in his cell and cuts him down. That act makes Studer doubt a case everyone else considers closed, and he reopens it by digging into Witschi's debts, family, and the village's leading men.
Once a person has a criminal record, police and community treat them as the obvious culprit, and every clue gets read to confirm that assumption. Stigma supplies the story of guilt. The system's efficiency depends on having pre-marked people to blame, so the outcast pays for crimes that respectable people commit.
In a small community, the notables who hold the offices, lend the money, and control the votes also decide what counts as suspicious. Read a local crime through who owes whom rather than who seems disreputable, and the respectable figures move to the center of the picture. The village's orderly surface is maintained by quietly expelling its outsiders.
Studer was once a commissioner and was knocked down to sergeant after crossing powerful interests in a banking affair. With no career left to protect, he can side with the people the institution has written off. His method is slow and physical: he sits in taverns, smokes his Brissagos, listens, and imagines himself into the suspect's position instead of running procedure. His outsider status inside the institution is what lets him see what it is built not to see.