Wright's book was developed out of five lectures he delivered at Westminster Abbey in 2003 and, in summary form, through a television program which first screened in the U.K. on Easter Day 2005. Its approach is biblical, practical, even intuitive, but not philosophical. As he states in his preface after reflecting on the recent natural disasters caused by tsunamis, hurricanes and earthquakes and the 9/11 attacks: "They are a reminder that 'the problem of evil' is not something we will 'solve' in the present world, and that our primary task is not so much to give answers to impossible philosophical questions as to bring signs of God's new world to birth on the basis of Jesus' death and in the power of his Spirit, even in the midst of 'the present evil age.'" This primary task underlies Wright's approach to what he calls, in chapter 1, 'the new problem of evil'. The old problem was a metaphysical question, asking why evil exists if there is a wise, good and supremely-powerful god. Contrary to some, Wright thinks this is a futile question, and one the Bible does not answer in any way satisfying to contemporary philosophers. The new problem in its present metaphysical form, he says, has been around for at least two-and-a-half centuries, beginning with the Lisbon earthquake on All Saints' Day 1755. He agrees with Susan Neiman's assessment in her book, Evil in Modern Thought, that Europe's philosophical history is best understood as people trying to cope or come to terms with evil. This includes Enlightenment-modern thinkers as well as postmodern ones. However, Wright sees the lines of thought that emerge from these attempts to understand the world in general and evil in particular as unsatisfactory. This includes the popular doctrine of automatic progress which, he affirms, post-modernism rightly deconstructed although it too leaves us without any satisfying solution. The 'new problem of evil' leaves us ignoring evil when it doesn't hit us in the face, surprised when it does, and reacting in immature, dangerous ways.
Wright seeks for a biblical, practical solution to evil that focuses on what God has done, is doing (including through us) and will do about evil. His summarizing journey through the scriptures is impressive, and his focus on the healing nature of divine and human forgiveness as rooted in "the victory of the cross" (favoring the Christus Victor theory of the atonement) is welcome. But take the book for what it's worth. It is not a comprehensive or balanced treatment either of the problem of evil or the meaning of Jesus' crucifixion, things which Wright admits in his preface. Although he asks the question "What is evil?" up front, one doesn't get anything like a definition until the middle of the book, in chapter 3: "Evil is the force of anti-creation, anti-life, the force which opposes and seeks to deface and destroy God's good world of space, time and matter, and above all God's image-bearing human creatures" (pg. 89). Again, his approach to evil is not philosophical. If you want to know "the ultimate reason why suffering exists," then see Suffering and the Sovereignty of God, edited by John Piper and Justin Taylor, where Piper offers a Christ-centered one, but don't expect it to be satisfying to many contemporary philosophers.
In addition to Neiman's book, mentioned above, Wright also references C.S. Lewis' The Great Divorce, Desmond Tutu's No Future Without Forgiveness, and Miroslav Volf's Exclusion and Embrace, among others, the last two relied on to expound on forgiveness in the last chapter. In terms of a recommendation, possibly no greater one can be given than that of Christian philosopher J.P. Moreland: "From now on, it should be the first work consulted by Christian philosophers and theologians working on the problem of evil, and pastors, laypeople and Christian workers should read and internalize the perspective of the book to insure a distinctively biblical approach in ministering to people in the face of evil."