Returned, Unharmed: A First Contact Thriller

Dara Voss has been salvaging in the asteroid belt for eleven years. She's good at finding things - less good at making them balance against a debt of 680, 000 credits that hasn't moved in most of that time. When a routine debris sweep flags an anomalous mass at bearing 227 - Arken composite, three hundred years old, two and a half centuries older than First Contact - she boards it expecting to find her way out of debt.
Instead she finds an archive.214 human subjects. 18th-century West Africa. Preserved in an alien cargo hold for three centuries by a system that was still running when Dara found it, patient in the dark. The collection dates to the height of the transatlantic slave trade. The subjects were returned to their lives afterward, their memories of the eighteen days removed so cleanly that no one who survived it ever knew.
And the neural tissue those eighteen days had produced - adapted under conditions of extreme and sustained duress - was exactly what an alien civilization needed to build the technology it would one day give humanity as a gift. The clean energy grid that now powers Earth's civilization, keeps its hospitals running, and sustains eight billion lives wasn't a gift. It was a payment. For sixty-one years of unconsented biological research on approximately four thousand enslaved people.
The Consortium that runs the solar system's economy has known for forty years. Inside the archive, Dara finds something the Consortium doesn't know about: a hidden record left by three members of the original mission crew - dissenters who spent their remaining centuries building a path to this moment. In it: the account of a woman named Abeni, written in Yoruba in 1775, who spent years reconstructing eighteen days she couldn't remember and asked one thing of whoever eventually found her words.
I was studied as a thing, not known as a person. I am writing this so that someone, eventually, will know me instead. Do something with the knowing. When the Consortium sends Internal Security operative Kael Orin to recover the archive, he brings a generous offer - and the verified mathematics of how many people die if the energy grid destabilizes. His numbers are real. So is Abeni's account. The question Dara has to answer is whether those two things are commensurable.
Whether there is a rate at which one converts to the other. Whether you can weigh the dead against the living, and what it makes you if you do. Returned, Unharmed is a first contact thriller about what gets taken without permission, what gets remembered against all odds, and what it costs to put a question into the world when the answer isn't clean. For readers of Dark Matter and The Expanse who want the working-class solar system - and a story that hits harder and stays longer.