The Lion the Witch and the Wardrobe
Chronologically as written, this was the first book of C.S. Lewis's Narnia series. Traditionally known as a book for children, I really enjoyed it as an adult. There are great over-arching character themes to think about such as deception, forgiveness, mercy, honor, fear and ultimately... redemption.
“Safe?” said Mr. Beaver; “don’t you hear what Mrs. Beaver tells you? Who said anything about safe? ‘Course he isn’t safe. But he’s good"