Rätsel der Nacht.

Professor Schott, director of the Oberland Mountain Observatory, has discovered a new star, which he names "Nova Hercules." Working alongside him are Dr. Gerellis and Dr. Alvens, both vying for the affections of the new assistant, Dr. Aenne Bruck, while the professor's wife, unhappy in her marriage, is interested in Dr. Gerellis and therefore wants a divorce. Due to the emotional entanglements, disappointment, and jealousy, considerable tension arises at the observatory. Then Professor Schott is found dead—poisoned with cyanide. Initially, Gerellis is suspected of the murder, but a photograph of the newly discovered star takes an unexpected turn.