On December 31, 2173, the "Ark Engine" on the far side of the moon started a seven-day cleaning process: all individuals with an entropy value above the threshold will be reset to zero.
Former genetic researcher Lin Qiubai, mechanics Xia Houjin, and Entropy Shang Xiaoman carried four vibrating knives and embarked on "Track Zero" - a retrograde road that traverses Folded China and goes vertically deep into the trench.
Within seven days, they must solve seven paradoxes, collect four "rewrite rights" votes, and choose between "return to zero" and "rewrite".
In the end, they left themselves in the trench forever, but let their shadows return to the ground with new physical constants.
The world was not saved, just the terms of the contract were rewritten.
