As the world rapidly changes under the influence of digital technology, Mr. Penumbra's 24-Hour Bookshop stands as a bridge between the past and the future. It is a place where pages hold not only knowledge, but also age-old secrets. An unemployed web designer takes a job as a night clerk at this mysterious bookshop, which has almost no customers but is full of strange old books and even stranger visitors. His new job gradually turns into an exciting adventure on the border between reality and technological magic. Gradually, the mysterious books and Mr. Penumbra himself lead the hero to uncover a secret organisation that has existed for 500 years.