Miss Marianne Beaumont, a spinster, and her younger sister are on their way home from a night at the theater when they come upon a townhouse fire. They stop to help the victims, including Mr. James Harcourt, a confirmed bachelor, and his parents Sir and Lady Harcourt. Although Mr. Harcourt distrusts the beau monde, he accepts Marianne's ministrations. That should have been the end of their association, but then a folded piece of paper shaped like a chameleon slips out of his mother's sleeve. It's an ornament Marianne has come across only one time before—next to her father's dead body. Recognizing that ornament—an orikata—might at last help her catch her father's killer, Marianne joins forces with Mr. Harcourt. He has a penchant for solving mysteries and has been searching for the elusive criminal who uses that identifier. Together—with a chaperone, of course—their investigations take them from one baffling clue to another. But the closer they get to finding their answers, the more they discover that all isn't as it seems, and the dangers are more sinister—and personal—than they'd realized.