Maaya is a teenager who can see ghosts, and she and her three friends get by on the poor streets of Sark by sealing away troublesome spirits under the direction of a deceptive, malicious wealthy man. Accompanying them is a ghost named Saber, Maaya's long-time friend. Maaya doesn't concern herself with world affairs, focusing only on staying alive in a superstitious town that ignores her at best and wants her dead at worst - but after an entire street of people goes missing without a trace and whispers of war begin to reach her ears, Maaya decides it's time to investigate.
Maaya soon finds herself in over her head as she confronts a wave of faceless ghosts that terrify even the dead. Driven on by rumors of a mysterious weapon that can make entire cities vanish in an instant, she and Saber start their journey across the world to find out how to stop it. She begins to find new friends, powerful allies, and even love, all while being pursued by new and more dangerous enemies.
The closer she gets, however, the more she realizes that the ghosts she's after may not just be mindlessly killing innocents - and that they may be chasing her instead.
Until now, Maaya and the others had been dealing with ghosts. Some were more troublesome than others, but Maaya had never felt particularly uncomfortable when dealing with the supernatural. Now, however, it had revealed itself to contain more mystery and power than she had ever thought possible. For all the experience she had, for all the knowledge she had accumulated over the years, she was back to feeling as though she knew nothing at all. She was a stranger in a strange world, one so infinite and broad in scope that it likely didn’t even realize, or care, that she existed.