The Ending of Death's End

Eighteen million years after the Three Body Problem inception, a Chinese couple finds refuge in a small universe. They receive a desperate message that the great universe (the one we live in) is doomed, because its total mass is not enough for its eventual collapse, so it is projected to expand endlessly, cool down and die. They sacrifice their own universe to add its mass to the great universe, so the cycle of collapse and re-birth may continue. The series ends with a Chinese communist exhortation that everyone has to sacrifice its private interests in order to save the collective. So, after a thousand pages of Trisolar invaders and their four dimensional weapons, we realize that we have never left contemporary China.