It follows three of the fiercest warriors in human history: a Viking raider guiding her young son on a bloody quest for revenge; a ninja in feudal Japan who turns against his Samurai brother in a brutal battle for succession; and a World War II pilot who takes to the sky to investigate an otherworldly threat to the Allied cause. But while all these warriors are killers in their own right, they are merely prey for their new opponent — the ultimate killer of killers.