Set halfway through Kratos' ten years of servitude to the Gods, Chains of Olympus begins with Kratos being dispatched to the city of Attica to help defend it from the invading Persian army. Soon after his arrival, the Spartan spots a basilisk climbing over the city walls and gives chase. During his chase, Kratos confronts the Persian King inside the city and kills him. Taking the King's power to summon the Efreet, he then encounters the basilisk and kills it. After defeating the basilisk, he witnesses the sun fall from the sky, plunging the world into darkness. Following the dim remaining light on the horizon, Kratos fights his way through the city of Marathon, along the way encountering the black fog of Morpheus, which now covers the land in darkness.