Bronze Age, one of the surviving ships from the Battle of Darkness, returns back to Earth after being told that they would be welcomed back as heroes. This warm welcome is not meant to be and as soon after they dock the entire crew is put on trial for crimes against humanity.
During the trial, it’s revealed that over 94% of the crew voted to attack Quantum during the Battle of Darkness, and even more gruesomely, they filled their food storage with the remains of the crew that they killed. Nearly the entire crew is convicted, but one of the members manages to send a communication to the other surviving ship of the Battle of Darkness, Blue Space, to tell them not to come back. In response, Gravity, a new fleet ship equipped with a gravitational wave antenna, is sent to pursue Blue Space along with two Trisolaran droplets.
Cheng Xin awakens from hibernation after 264 years which is now 61 years into the Deterrence Era. She finds a much different world than the one that she left. The world is much more feminized, humans and Trisolarans are working together and sharing science and culture, and the star that she was gifted by Yun Tianming turns out to have planets after all.
The planets were discovered by an astronomy PhD named 艾 (Ai) AA. Cheng Xin comes to an arrangement with the UN to sell the planets and the license for the stars’ energy but retains the star itself, since she doesn’t want to sell what was a gift. With the large proceeds, she and AA form a new company.
In the years since Luo Ji first discovered and implemented deterrence, he now singularly holds the deterrence mechanism which is now a gravitational wave broadcast system, which he will activate in the event that Trisolarans break the peace. At over 100 years old, and suspected of mundicide for his spell, the public urges someone else to be elected to take over his position, referred to as Swordholder.
One person who very much wants the job is PIA chief Thomas Wade, who also hibernated to now. He fears that Cheng Xin would beat him out for the role, despite her not even being aware of what it is, and tricks her into a secluded area and shoots her with a common era gun, only to be stopped by AA and police before he can kill her.
Meanwhile, In the vicinity of the Oort Cloud, Gravity nearly catches up with Blue Space when the crew notices some strange phenomena. From holes in walls, micrometeorites, and large parts of the ship disappearing temporarily, the crew isn’t sure what to make of it. After Blue Space surrenders, Gravity receives an alert that the droplets are attacking.
Cheng Xin, who feels a maternal sense of protection for this new world, eventually wins election as the new Swordholder to succeed Luo Ji. She meets him in the bunker deep underground for the handover ceremony, where he has been literally wallfacing for over half a century to keep the Trisolarans at bay. However, her new position was only destined to last a mere 15 minutes.