Mathias, an Alsatian innkeeper, murders a rich Pole staying at his inn But Mathias' conscience will not let him rest, and the murdered man's spirit drives the innkeeper nearly mad. The victim's brother calls for an inquest and brings with him a sideshow mesmerist supposedly able to read minds. Mathias, as burgomaster, is called upon to conduct the inquest, but under the intuitive eye of the mesmerist cannot resist torment of his own conscience.