Warmaster Horus has a Mechanicum ally on Mars. But the problem is that he wants Mars, a military factory planet, to be completely under his control as Horus plans to invade Imperial Earth. So, there will be a civil war on Mars until one is destroyed...

This is the ninth book in the Horus Heresy series. You will need to read the other eight books to know what is going on.

Good story. Graham McNeill makes these strange cyborg wizards come to life. Highly recommended to dark war sci-fi and/or fans of Warhammer 40,000. ~~ Jeffrey Lu