I am an ordinary sort of fellow, not braver than other people, but I hate to see a good man downed, and that long knife would not be the end of Scudder if I could play the game in his place.

Hannay reasons this out after he discovers Scudder's dead body in his flat. He is afraid that Scudder's fantastic story won't be believed. He fears he will be charged with murder and hanged or put in jail. But most of all, he wants to right wrongs. This illustrates an important theme of the book: an ordinary person becomes a hero by standing up with courage to defend honor and country.

The capitalists would rake in the shekels, and make fortunes by buying up wreckage. Capital, he said, had no conscience and no fatherland.

The above quote is the American Scudder's explanation for the plot to start a war between Germany and Russia that he has uncovered. It's a money-making scheme. The word "shekels" is associated with Jews, and Scudder will soon go on to tell Hannay that the Jews are heavily involved in the plot, both to make money and to get revenge on Russia for the pogroms. The book's casual anti-Semitism can be shocking to a modern audience, showing that 1915 was a very different time from the twenty-first century. But "follow the money" works in both centuries.

Contrary to general belief, I was not a murderer, but I had become an unholy liar, a shameless impostor, and a highwayman with a marked taste for expensive motor-cars.

Hannay might be an ordinary man thrust into the dangerous situation of being pursued by cold-blooded murderers, but his new life is not without its compensation. He's having the adventure of a lifetime, getting to do something that was, at the time, reserved for the wealthy (drive around in a car), and the boredom which almost sent him back to Africa has disappeared. This book may not be a prose masterpiece, but the opportunity for the reader to put themselves in the shoes of an ordinary person having an extraordinary experience adds to the book's appeal.