Spiral : Invasi dari Perut Bumi

The concept of hidden depths and secret societies really intrigued me. I wonder what sparked the author's imagination to set the story there.

The story had some really exciting moments but also parts where it felt like things dragged a bit. Was that intentional to build suspense?

The detailed descriptions made the world feel so real. I'm curious whether the author drew from real places or built it entirely from imagination.