Children have always disappeared under the right conditions - slipping through the shadows under a bed or at the back of a wardrobe, tumbling down rabbit holes and into old wells, and emerging somewhere...else. But magical lands have little need for used-up miracle children. Nancy tumbled once, but now she's back. The things she's experienced...they change a person. The children under Miss West's care understand all too well. And each of them is seeking a way back to their own fantasy world.

Avery is an exceptional child. Everything he does is precise, from the way he washes his face in the morning to the way he completes his homework - without complaint, without fuss, without prompt. Zib is also an exceptional child, because all children are, in their own way. But where everything Avery does and is can be measured, nothing Zib does can possibly be predicted, except for the fact that she can always be relied upon to be unpredictable. They live on the same street. They live in different worlds.

Ellingham Academy is a famous private school in Vermont for the brightest thinkers, inventors, and artists. It was founded by Albert Ellingham, an early 20th century tycoon, who wanted to make a wonderful place full of riddles, twisting pathways, and gardens. "A place," he said, "where learning is a game." Shortly after the school opened, his wife and daughter were kidnapped. The only real clue was a mocking riddle listing methods of murder, signed with the frightening pseudonym "Truly, Devious".

In a corporate-dominated spacefaring future, planetary missions must be approved and supplied by the Company. Exploratory teams are accompanied by Company-supplied security androids, for their own safety. But in a society where contracts are awarded to the lowest bidder, safety isn’t a primary concern. On a distant planet, a team of scientists are conducting surface tests, shadowed by their Company-supplied ‘droid—a self-aware SecUnit that has hacked its own governor module, and refers to itself (though never out loud) as “Murderbot.”

All across the world, people look up at the moon and dream of gods. Gods of knowledge and wisdom, gods of tides and longevity. Over time, some of these moon gods incarnated into the human world alongside the other manifest natural concepts. Their job is to cross the sky above the Impossible City—the heart of all creation—to keep it connected to reality. And someone is killing them. There are so many of them that it's easy for a few disappearances to slip through the cracks. But they aren't limitless.