In a stately Zurich Villa, an unexplained case of fire results in a fatality. Was it arson, and if so, what could have been the motive? Greed, sabotage? Or was the cause simply carelessness? The narrator, a disillusioned journalist, is hired to play detective. His client is a former tobacco merchant who became a missionary do-gooder in old age. The old man wants to know more about the life of his nephew, an engineer, who looks critically at social trends. Underlying the investigation of the fire case, there is a quiet struggle between the journalist's moral attitude and the engineer's sense of responsibility. In the end, they both contribute to the solution of the fire case.