The basic storyline of this book is the beginning of Narnia. Polly and Digory are not allowed in Digory's Uncle Andrew's office. They accidentally go in there and find themselves in another world when they put rings on. Digory's mom is sick and he wants to find a cure for her. He and Polly find themselves in Narnia and Aslan is there and he finds a cure or her and it works. Digory grows up and has a wardrobe and doesn't know that Narnia is behind all of the coats in there.
All C.S. Lewis books.
Yes, I would recommend this book for all ages.