For thirteen years, historian Adam Voss asked the Mordhai ? a technologically advanced, deeply hierarchical civilization on the edge of known space ? for access to their archives. For thirteen years, the answer was the same: polite silence.

Then, without warning, the Mordhai ask for him. By name.

What Adam finds in Mordhai territory isn't the raw, hostile civilization he expected. It's worse, in the most seductive sense of the word: floating cities of impossible beauty, technology that makes everything his people have built look primitive, and a caste system no one there seems to find strange ? not the inequality itself, but the ease with which it's lived.

At the center of it all is Kaeth Mordh, a being who never threatens, never raises his voice, never needs to. He offers. Always exactly what Adam didn't know he needed to hear. It's only afterward that the question arrives: what was traded in return?

Alongside Toma, a young Mordhai interpreter risking everything to trust an outsider, Adam begins to uncover fragments of something the Mordhai only speak of in lowered voices, and only when they're certain no one else is listening: a force they call the Consumption.

The Caste of Silence is the fifth book in The Aurion Legacy, a hard science fiction saga about the kind of threat that's recognized too late ? because it never looks like a threat while it's happening.

Continues the saga that began in Stellar Exodus.