“Activate the travelers.” With those three words, The Master, leader of the Kuiper Knights, unleashed a horrific terror attack on the United Nations of Terra that united the entire planet against them. Major Abner Fortis takes command of Second Battalion of the First Regiment of the newly reconstituted Second ISMC Division and joins the force deployed to the Free Sector to mete out punishment to the evildoers. Using out-of-the-box thinking and old-school Space Marine attitude, Fortis recruits his best friend, Gunnery Sergeant Petr Ystremski, to serve as First Sergeant and whips the battalion into fighting shape in short order. But when tragedy strikes during the combat drop, the regimental battle plan is thrown into disarray and the Kuiper Knights—many of them former Space Marines—are able put up a stiff resistance. With another battalion under siege and the chain of command stunned into inaction, it falls on Fortis and Second Battalion to take decisive action to head off disaster. Outnumbered five to one, with their enemy dug deep into a seemingly impregnable position, can Fortis and the Space Marines prevail and deliver the justice they’ve come to dispense, or will the Space Marines suffer a catastrophic defeat at the hands of the Knights?