The Silent House by Fergus Hume

Nowadays, events, political, social, and criminal, crowd so closely on one another's heels that what was formerly a nine days' wonder is scarcely marvelled at the same number of minutes. Yet in certain cases episodes of a mysterious or unexpected nature engage the attention of a careless world for a somewhat longer period, and provoke an immense amount of discussion and surmise. In this category may be placed the crime committed in Geneva Square; for when the extraordinary circumstances of the case became known, much curiosity was manifested regarding the possible criminal and his motive for committing so apparently useless a crime.

To add to the wonderment of the public, it came out in the evidence of Lucian Denzil at the inquest that Berwin was not the real name of the victim; so here the authorities were confronted with a three-fold problem. They had first to discover the name of the dead man; second, to learn who it was had so foully murdered him; and third, to find out the reason why the unknown assassin should have slain an apparently harmless man.