As the ork menace ravages the galaxy, the Imperium faces its darkest hour. Its fleets are in ruins, its armies devastated amongst them the noble Imperial Fists and even a primarch of myth has fallen against the Beast. As brute force fails, Koorland resorts to increasingly desperate tactics against the greenskins. A final hope lies in deploying the controversial Deathwatch and the Sisters of Silence in a deft strike at the heart of the ork empire. As the situation grows more dire, Koorland must live up to the symbol he has become as the last son of Dorn or all of humanity will be doomed.

Read it because

It's the true turning point of The Beast Arises series, when everything changes. We won't say any more: just read it and see.