This is a solid book, though not a great one. It is a survey of the lives and teachings of five leading evangelicals of the past half century. The five leaders are John Stott, Martyn Lloyd-Jones, Francis Schaeffer, James Packer and Billy Graham.
John Stott was a British pastor, author and international leader for evangelicals. He is my single all-time favorite commentator on the biblical books he wrote on.
Martyn Lloyd-Jones was a pastor in London for decades. Many regard him as the greatest preacher of the 20th century. He was a medical doctor who became a pastor at a young age and seemed to have a special anointing as a preacher.
Francis Schaeffer was an American who spent most of his life in Switzerland. He and his wife had a ministry there for young people throughout the world who gravitated to their home in Switzerland with all kinds of questions. He also wrote extensively.
J.I. Packer is most famous for writing the book Knowing God, one of my all-time favorites. But he is a scholar of the first rank and has written many other books and articles.
Billy Graham is the well-known evangelist, certainly the greatest evangelist of the 20th century.
This is a helpful overview.