The Lion, the Witch, and the Wardrobe: The Chronicles of Narnia

Lucy is the first to find the secret of the wardrobe in the professor's mysterious old house. At first her brothers and sister don't believe her when she tells of her visit to the land of Narnia. But soon Edmund, then Peter and Susan step through the wardrobe themselves. In Narnia they find a country buried under the evil enchantment of the White Witch. When they meet the Lion Aslan, they realize they've been called to a great adventure and bravely join the battle to free Narnia from the Witch's sinister spell.

This was the first book written in The Chronicles of Narnia. It now stands as the second book in the series, preceded by The Magician's Nephew.