"Keys to the Kingdom" is a popular fantasy book series written by Garth Nix. The story follows a young boy named Arthur Penhaligon, who discovers he is the heir to a magical realm known as the House. This realm is filled with unique characters and challenges, as Arthur learns about his responsibilities and the powers he possesses. The series combines elements of adventure, magic, and mythology, exploring themes of courage and identity. As Arthur navigates the complexities of the House, he encounters various allies and adversaries, each contributing to his growth and understanding of his role in this fantastical world.