New York in the 40s. Lilian Pentecost is the most famous private detective in town, but her health is beginning to fail her. After meeting Miss Parker, she decides to hire the girl as an assistant. After all, Willogin has a unique set of skills: she skillfully throws knives, picks any lock blindfolded, and easily puts men twice her size on the shoulder blades.

The extraordinary couple soon has to investigate a mysterious murder case. A famous fortune teller is invited to the Collins mansion for a Halloween party. After a seance, Abigail, the mistress of the house, is found dead. The office is locked from the inside, no visible evidence. And the only clue is a bloody crystal ball...