Judgment of Mars (Starship's Mage Book 5) by Glynn Stewart

A war fought in the shadowsA conspiracy shattered in fireA moment of weakness… When politics are played for blood. The destruction of the secret archive of the Royal Order of Keepers on Mars has left Damien Montgomery, Hand of the Mage-King, with his enemies defeated, his lover dead–and his questions unanswered. When he seeks out the remaining Keepers for answers, he discovers only violence and death in their strongholds. Someone else is hunting down the survivors to make sure they never answer Damien’s questions–or anyone else’s. As a wave of murder sweeps Mars and the consequences of the Keepers’ conspiracy sink home, Damien is summoned before the Council of the Protectorate to answer for the deaths of two other Hands. In the political heart of the Protectorate of Mars, he finds he may be forced to choose between honoring the oaths he swore and preserving the survival of the Protectorate itself!