I have just finished this book and have to say, I concur with Kingsley Amis (writer of the introduction) who said that it was the "most thrilling book he has ever read." Chesterton weaves together a combination detective story, wierd dream ("Nightmare" as he says on his cover page), and social commentary. It's certainly not an apologetic book (as C.S. Lewis said, one can't always be defending the faith, sometimes one has to encourage those already converted), but elements of Christianity do come through (especially Chesterton's sensible view that your faith should affect every area of your life and outlook to the world). The hero, Symes (who is called Thursday) is a detective and a Christian who provokes an anarchist and infiltrates a world-wide underground anarchist society. From there, I won't spoil the story but there are many adventures, twists, and turns. This part I thought very well written. Every new discovery Symes makes literally had me on the edge of my seat. Things become more and more bizarre (right in line with Chesterton's own description of his book as a "Nightmare") until a very bizarre ending that I confess I have still not fully absorbed. There is a great deal of symbolism and allegory in the book, which is not clear until at least a third of the way through the book. In this way, the book is similar to C.S. Lewis's book "That Hideous Strength" (the third book in his space trilogy that includes "Perelandra"). Like Lewis's book, "Thursday" starts off very realistic (although with some hints of the bizarre twists to come) and gets more and more strange as the book goes on. Two things that will be helpful to understanding much of the symbolism: (1) Read the afterword at the end of the book by Chesterton. Unlike Amis's introduction, I wouldn't read it before you start reading the book. I'd recommend reading it after about a third of the book, perhaps right around the time the Pole is "unmasked" (that is, around chapter 6). (2) Also helpful is Martin Gardner's commentary on the book. There is another edition of the book that has Gardner's comments, but the most important parts of his commentary are available on the Internet (just search ye shall find them). This lays out the symbolism in more detail than the former, so if you want to figure it out for yourself don't read this until the end of the book. Finally, after you read through the book once, think about it and read comments such as Gardner's, then go back and read it again. As Amis says in his introduction, you can read this book many times and get new things out of it every time.