In this intricately plotted crime comedy, Johannes Heesters plays the worldly insurance detective Peter Holm, who is determined to apprehend jewel thief Robert Makaroff. To this end, Holm travels to Copenhagen, where the Hungarian actress Lilly Hegedüsch is staying at a luxury hotel with her rare jewelry. While Holm is searching for Makaroff, Jenny, the sleuthing daughter of Holm's boss, arrives in Copenhagen. Since Jenny doesn't know her secret admirer Holm, numerous mix-ups and suspicions ensue before the rival detectives become lovers.