Evil and the Justice of God (2006) is a concise treatment of the problem of evil and why the Christian response makes sense. Through five relatively long chapters, Wright explores why evil acts seem so extreme to our postmodern sensibilities, and why the biblical story anticipates and expects evil. He walks through the Old Testament and New Testament and explains how kingdom Christians can respond to evil. He concludes by looking at the necessity of forgiveness as the response to evil, both societally and in one on one circumstances.
This book would be a nice addition to John Stott's The Cross of Christ and Randy Alcorn's If God is Good. He acknowledges the reality of evil, the necessity of the cross, and the importance of ongoing forgiveness.
Wright also reminds me why I like many British authors. They tend to write very well, and possess a humility that seems absent from many Americans.
If you want to explore the topic of evil, Wright's book is a fine place to start.