As Super-Typhoon Baiyue makes landfall at the Han frontier watchtower, Zetian works on annotating the Book of Laborism while ignoring Qin Zheng's daily nagging messages, relayed through Yizhi to Wan'er. Taiping, Di Renjie, and Wan'er pass the time with her, with Di Renjie sharing his proposed amendments to Qin Zheng's legal code emphasizing rehabilitation over punishment. Zetian privately reflects that Di Renjie's idealism is unworkable in their circumstances.

The watchtower is suddenly rammed by Hunduns; no sirens warned them. Zetian and Di Renjie struggle through the typhoon to her Chrysalis, the Nine-Tailed Fox, which is teetering under attack. She launches them into the cockpit and rises into Ascended Form, finding the ocean has flooded up to the Great Wall. She discovers a Prince-class Earth-type Hundun coordinating common Hunduns to ram a dent into the Wall.

Zetian engages the Prince but cannot stop the smaller Hunduns from breaking through the Wall. Hunduns pour into Huaxia. She wedges the Fox into the breach to stop the influx, impaling the Prince when it charges, but it eventually retreats into the storm. Overwhelmed by smaller Hunduns climbing the Fox, Zetian realizes she has failed her primary duty as a pilot, and the sabotaged sirens point to reactionary engineers.

Liang Yuhuan arrives in the Plum Blossom Deer, having tracked the Hunduns. She ascends her Chrysalis into humanoid form and offers to plug the breach so Zetian can hunt the breachers. They swap positions, and Zetian races into Huaxia, picking off Hunduns one by one as the storm subsides.

Pursuing the final Hundun to a destroyed village, Zetian kills it and discovers a shivering little girl in a collapsed cellar beside the crushed bodies of what appear to be her parents, leaving Zetian stunned with horror at the human cost of the breach.