The son of an Argentine chemist travels to Vienna, to solve the murder of his father. Step by step, he realizes that his father was internationally entangled in secret service machinations and chemical weapon sales, and ends up in mortal danger himself. Meanwhile, he also realizes that there is no connection between his father's murderess and those dubious activities. Her motive for killing him goes back much futher, to a court hearing during the Third Reich...

Landowner Klapproth would love to have his nephew Alfred show him the inside of an insane asylum and meet real lunatics, promising to financially support him in starting a business. Alfred's friend Ernst Kissling recommends that he show his uncle the Schöller Guesthouse, whose guests are quite eccentric. Landowner Klapproth, who truly believes the guests to be lunatics, is thoroughly amused.