The Magician's Nephew
by C. S. Lewis

Digory and Polly meet and become friends one cold, wet summer in London. Their lives burst into adventure when Digory's Uncle Andrew, who thinks he is a magician, sends them hurtling to… somewhere else. They find their way to Narnia, new-born from the Lion's song, and encounter the evil sorceress Jadis before they finally return home.