Lottie Sprigg and her employer, Mrs Moore, are guests at Vienna's opulent Schönbrunn Palace. But their visit goes awry when the corpse of a renowned psychoanalyst is found in the grounds. There's a handful of suspects and - tragically for Mrs Moore - one of them is her beloved Prince Manfred. Mrs Moore is devastated that her beau has been caught up in the crime. And she soon discovers he's been keeping other secrets from her, too. Lottie is tasked with proving Prince Manfred's innocence. But with overwhelming evidence against him, has she any chance of success? As she scours Vienna for clues, Lottie wonders if the jolly Bavarian prince has been hiding a darker side all along...