In timeline, Killzone 2 follows after Killzone and Killzone: Liberation, and takes place entirely on Helghan, the home-world of the Helghast who invaded an Interplanetary Strategic Alliance (ISA) colony in previous Killzone installments. Two years after the Helghast assault on Vekta, the ISA is taking the fight to the enemy's home world of Helghan. The ISA goal is direct: capture the Helghast leader, Emperor Visari, and bring the Helghast war machine to a halt. Sev discovers his squad is not just fighting enemy forces – their fiercest opponent may be the planet itself.