The Magician's Nephew by C. S. Lewis

The book is a prequel to the popular fantasy series, and tells the story of two children who stumble upon magical rings that transport them to different worlds. They encounter a wicked queen, awaken a powerful lion who creates a new world, and inadvertently bring the queen into this new world, setting the stage for the rest of the series. The book explores themes of creation, temptation, and the consequences of one's actions.

The 1655th greatest book of all time