Since the death of her father, March Middleton has been living with London's most famous private detective, known for his brilliance and gruff demeanor. One day, she receives an invitation from a completely unknown uncle to his villa, which she follows. Her new uncle is charming and eccentric - and the next morning, he's found dead. Before March has the chance to uncover what happened in Villa Saturn, she becomes the focus of the investigation. She has no choice but to ask Sidney Grice for help. However, he has serious doubts about her innocence. And the more he discovers about the case, the more all the evidence points to him...