Set halfway through Kratos's ten years of servitude to the gods, Chains of Olympus opens with Kratos dispatched to the city of Attica to help defend it from the invading Persian army. Soon after arriving, the Spartan spots a basilisk scaling the city walls and gives chase, confronting and killing the Persian King along the way and taking his power to summon the Efreet, before slaying the basilisk as well. In its wake, Kratos watches the sun fall from the sky, plunging the world into darkness. Following the last dim light on the horizon, he fights his way through the city of Marathon, encountering the black fog of Morpheus that now blankets the land in shadow.