Nightwatch on the Hinterlands

Set in the universe of Rory Thorne, this new sci-fi mystery follows an unlikely duo who must discover the motive behind an unusual murder.
THE TEMPLAR: When Lieutenant Iari hears screams in the night, she expects to interrupt a robbery or break up a fight. Instead she discovers a murder with an impossible suspect: a riev, one of the battle-mecha decommissioned after the end of the last conflict, repurposed for manual labor. Riev don't kill people. And yet, clearly, one has. Iari sets out to find it.
THE SPY: Officially, Gaer is an ambassador from the vakari. Unofficially, he's also a spy, sending information back to his government, unfiltered by diplomatic channels. Unlike Iari, Gaer isn't so sure the riev's behavior is just a malfunction, since the riev were created using an unstable mixture of alchemy and arithmancy.
As Gaer and Iari search for the truth, they discover that the murderous riev is just a weapon in the hands of a wielder with wider...