The Midnight Library is a thought-provoking speculative novel about Nora Seed, a woman who finds herself in a mysterious library between life and death. Every book in the library contains a different version of her life, based on choices she could have made differently. She gets the opportunity to explore these alternate lives and reconsider her regrets, ambitions, relationships and idea of happiness.

Through Nora's journey, Matt Haig explores regret, choice, possibility, identity and what makes a life meaningful. The novel blends contemporary fiction with elements of fantasy and philosophical fiction, ultimately asking what it means to live a fulfilling life.