Doubling for penalties increases the stakes and raises the blood pressure. For this you need confidence, and that is where tight defense plays a crucial role. Good defenders risk more penalty doubles. Demon Doublers are not born; they rise from the ranks of Demon Defenders. That is why this book begins with defense, to build a confident foundation for doubling. A sound bidding style also helps: it inspires confidence to know that partner has his bids.
This is not a book for beginners; I assume you know your basics about leads and signals. It teaches you how to use defensive information. The Socratic method (constant questioning) that I use promotes logical thinking in a way that promulgating rules cannot.
By the end of Part I, as a graduate Demon Defender, you should be primed for the adventurous world of penalty doubles. Part II explains when to double (and when not to) and shows how defending doubled contracts, especially partials, has a rhythm of its own. When you have absorbed the lessons in this book, be prepared for a change in your bridge life. You will win more—a lot more.