As the London nights darken, rumours spread about the devil’s chariot, which preys on young women walking alone at night. Novice private investigator Liberty Lane has no time for such horror stories, so when a poetic young man begs her to find his missing fiance, she accepts, suspecting there is a more prosaic explanation. Meanwhile, she is engaged to help prevent a royal scandal involving Prince Albert’s worldlier brother, Prince Ernest. Liberty begins work on both cases, but when young women begin showing up dead, the tales of the devil’s chariot don’t seem so ridiculous any more.