Warhammer 40k Fire Caste

"In the jungles of the Dolorosa Coil, a coalition of alien tau and human deserters have waged war upon the Imperium for countless years. Fresh Imperial Guard forces from the Arkhan Confederates are sent in to break the stalemate and annihilate the xenos. But greater forces are at work, and the Confederates soon find themselves broken and scattered. As they fight a desperate guerrilla war, their only hope may lie in the hands of a disgraced commissar, hell-bent on revenge."