Miss Newberry is one of the first fierce female private detectives in literature. Let the author introduce her: "The elevator boy tossed her a kindly grin as she stepped into the elevator. But she seemed not to notice. She was a small woman in gray - gray eyes and hair, and the close-fitting suit and small hat were of soft gray. Anyone passing her in a crowd would not have noticed her. There might have been the sense of something pleasant that had passed - a subtle perfume that came elusively, but nothing to recall. The only bit of color about her was a knitted green silk purse in her hand, with curiously wrought gold fittings. It went oddly well with the gray dress and hat."
She operates as SWAT. Her special "weapon and tactic" is her knitting: to calm down clients and suspects, and make notes - into the knitting. In this novel, she finds an emerald necklace, which was hunted for in vain by several detectives.