In a world where Magecraft clashes with science, the Chaldea Security Organization gathers experts in both to save humanity from extinction. Ritsuka Fujimaru, the last Master, and the Demi-Servant Mash Kyrielight venture into historical Singularities, mysterious realms threatening humanity's survival. Their latest mission takes them back to ancient Mesopotamia, facing King Gilgamesh and his city of Uruk under siege by goddesses and Demonic Beasts. With time travel and valor, they fight to protect a civilization on the edge of collapse, where mortals and deities clash in a battle for the future. As fate unfolds, Fujimaru and Mash, veterans of past challenges, brace for their ultimate showdown against overwhelming forces.