A Severe Mercy
by Sheldon Vanauken

The author tells a moving story of love and faith, and how those bulwarks supported him and his wife through the valley of the shadow of death. The Vanaukens became friends with C.S. Lewis, and this book provides a special glimpse into Lewis' character.

This is one of the most intensely personal books I've read. It is almost uncomfortable at times (and a few comments are actually uncomfortable), but it provides beautiful reflections on God's dealings with his people.