Episcopal Bishop N.T. Wright is one of the foremost scripture scholars on St. Paul. HIs mission has been to save Paul from some of the distortions of the Reformation. Paul's major concerns about the 'works of the law' really amount to an objection to circumcision and kosher laws. Paul, a devout Pharisee, sought to bring Gentiles into relationship with the people of Israel by baptizing them into the person of Jesus of Nazareth.
This book by Bishop Wright tries to bring the life of Paul alive in the readers imagination. Along the way each of the Pauline letters are put into a context that brings them alive. I recommend almost anything that Bishop Wright writes and I have read four or five of his books. This one is available in hardcopy, on Kindle and on Audible. If you are on a road trip, it is a great listen. I refer back to this book constantly as Paul's letters are part of the readings at Mass or in the Breviary almost daily.