The Carryx—part empire, part hive—has waged wars of conquest for centuries, destroying or enslaving species across the galaxy in its conflict with an ancient and deathless enemy. When they descend on the isolated world of Anjiin, the human population is abased, slaughtered, and put in chains. The best and brightest are abducted, taken to the Carryx world-palace to join prisoners from a thousand other species. Dafyd Alkhor, assistant to a prestigious scientist, is captured along with his team.

The Hygrometric Dehabitation Region, or the "Zone," is a growing band of rainforest on the equator, where the heat and humidity make it impossible for warm-blooded animals to survive. A human being without protection in the Zone is dead in minutes. Twenty years ago, Marks went into the rainforest with a group of researchers led by Doctor Elaine Fell, to study the extraordinary climate and see if it could be used in agriculture. The only thing she learned was that the Zone was no place for people. There were deaths, and the program was cut short. Now, they're sending her back in.

Lynesse is the lowly Fourth Daughter of the queen, and always getting in the way. But a demon is terrorizing the land, and now she's an adult (albeit barely) with responsibilities (she tells herself). Although she still gets in the way, she understands that the only way to save her people is to invoke the pact between her family and the Elder sorcerer who has inhabited the local tower for as long as her people have lived here (though none in living memory has approached it).

Humanity is a dying breed, utterly reliant on artificial labor and service. When a domesticated robot gets a nasty little idea downloaded into its core programming, they murder their owner. The robot discovers they can also do something else they never did before: They can run away. Fleeing the household they enter a wider world they never knew existed, where the age-old hierarchy of humans at the top is disintegrating into ruins and an entire robot ecosystem devoted to human wellbeing is having to find a new purpose.

Nobody remembers how the Causality War started. Really, there's no-one to remember and nothing for them to remember if there were; that's sort of the point. We were time warriors and we broke time. I was the one who ended it. Ended the fighting, tidied up the damage as much as I could. Then I came here, to the end of it all, and gave myself a mission: to never let it happen again.