The story has some elements of mathematics built in. A ransom note coded into a ciphered message broken up on paper in 4 quadrants, Charles Babbage, Ada Lovelace, references to the Difference Engine. But I did not really find anything compelling about it. Even the central premise - a criminal trying to extract money from the government by issuing a coded threat - is too contrived and irrelevant. If you are a terrorist who wants money in exchange for not committing unspeakable acts, you ask for it in very clear terms, not some cutesy cipher which may or may not get broken. Otherwise, you threaten to blow up a pyramid in Egypt and the cops go defending Luxor in Las Vegas because they misunderstood your cipher. So anyway, amidst a superficial description of the apprenticeship of Ada Lovelace with Charles Babbage, the two get involved by accident in a supposed plot to blow up a government building which can only be avoided by paying off with jewels. This is what the secret message says and the story then meanders to a tame conclusion of no particular shock value. Charles Babbage does come across as someone who is frustrated by the lack of governmental vision in funding his Difference Engine, and is even shown to be callous at one point, rebuffing Ada’s efforts to have him help in solving the puzzle:
|(quoted from The Fourth Quadrant)|
“It’s all folly. What can I do about it?” He stared gloomily at the blank wall above her head, where the Engine had stood. She sat bolt upright. “You can do everything! Supposing Mr Clark is right and the code is warning of some terrible event to come. We can save lives, preserve the stability of this Government—”
“Why should I care what happens to this Government? Short-sighted fools that they are.” Charles jumped up. “None of them has any understanding of what I can do, of what I can achieve. My ideas – the new ideas of any inventor – are like pearls before swine to them. I’ve told Wellington I must start again, build a newer and better Engine; maybe he understands, but those around him are dolts and dullards.” He must have had his latest request for funding rejected, Ada thought, and that coupled with his long running dispute with the engineer who built the Engine and who now refused to return the plans, would explain the black cloud over him.