War of the Marionettes — Adam-Troy Castro

Andrea Cort, protagonist of Emissaries From The Dead and The Third Claw of God, returns with her lovers Oscin and Skye Porrinyard for a visit to the distant planet Vlhan, whose towering inhabitants regularly gather for a ritual that is half art-form, half-suicide. Once before, the ritual went wrong, and became a bloody assault on human beings...but that's history now, and Andrea seeks only information in the ongoing mystery that has come to consume her life.

Unfortunately, a young girl has gone missing on Vlhan...and Andrea has arrived just in time for the killing to begin again.