A Tiding Of Magpies

In the 26th century, the Human Empire is fighting a time war with a mysterious race of shape-shifters. An elite unit, the Space/Time Axial Response Team, is responsible for policing the timeline, seeking out temporal interference and dealing with it.But with a traitor in the ranks, the war is going badly for them, and the enemy is building towards a final cataclysmic blow against humanity... time is, literally, running out