A sudden extreme cold apocalypse strikes, plunging the entire world into a frozen state. Protagonist Lu Yan, relying on his modern scientific knowledge, transforms an abandoned granary into a constant-temperature underground fortress, sets up physical defenses to fend off looting survivors, and resolves a deadly crisis to save a desperate mother and child. He survives the long harsh winter through rationality and resilience, leading the group to rebuild order and start a new life from the ruins.