The Red Waaagh! has come to the Sanctus Reach. Grukk Face-Rippa, an ork warboss as cunning as he is brutal, leads a mighty invasion force to Alaric Prime and its sister worlds. As the earth shakes beneath their assault, the warriors of the Astra Militarum, the noble Imperial Knight houses of Alaric Prime and the savage Space Wolves lead the counter-attack – and Grukk faces a threat from within his ranks as Big Mek Mogrok plans to oust him and take control of the Red Waaagh! for himself.