Two years after the Helghast assault on Vekta, the ISA is bringing the fight to the enemy's home world of Helghan. Taking the role of Sev, the battle-hardened veteran of the special forces unit known as the Legion, players will embark upon a mission to the planet Helghan to capture the Helghast leader, Emperor Visari, and bring the enemy's war machine to a halt. For Sev and his squad, the invasion of Helghan is just the beginning. Tasked with securing Pyrrhus, the Capital City, the team quickly discovers that the Helghast are a formidable enemy on their home planet. Not only have they adjusted to the planet's hostile conditions, they have also harnessed a source of power from the environment that can be used against the ISA. Sev and his team soon discover the fight is greater than simply addressing the enemy forces; the Legion must also learn how to handle the effects of the fierce enemy planet.