On April 1st, 20XX, a massive meteorite strikes Antarctica, and three months later, the "X Virus," also known as the zombie virus, spreads globally. The world quickly descends into chaos as governments lose control and society collapses.

The story focuses on Tang Buping, a young man living a desolate life in a tiny, dilapidated wooden cabin near the Huangpu River. After his mother's death three years prior, he was cast out and has been living like a zombie himself, full of despair. One day, while searching for food, he is attacked by a zombie and barely escapes back to his cabin. Ready to give up and lie down to await death, he writes a final letter to his deceased mother.

However, as he lies on his bed, he unexpectedly awakens the "Lie Flat and Develop" system. The novel follows Tang Buping as he uses this new, seemingly tower-defense-oriented system to survive and perhaps even thrive in the harsh, zombie-infested apocalypse.