This book, as one might guess from the title, is about Confession. It is about more of course, since repentance is a very wide-reaching and profound aspect of Orthodox spirituality, and certainly is not limited to Confession. However, those who are looking for a book about private repentance will be let down by this book. It is about "The Mystery of Repentance," as the sub-title says. Of course, this can be taken in a number of ways. Such an intimate thing as repentance--the meeting of God and Man through Prayer--is in many ways a mystery. But in this case, by Mystery the author means Sacrament (the Greek Mysterion is roughly equivalent to the Latin Sacramentum, I've been told).
The book is a very good overview of the Orthodox Sacrament of Confession. It deals with the how's, why's, and even addresses some of the objections that sometimes pop up. This book is not for those who are lax or lazy spiritually, and get defensive when confronted. This book doesn't beat around the bush, and puts the Orthodox faith forward straightly, without sugar-coating.