The Calamity of Longyuan

In the spring of the second year of Xiangxing, the exiled Southern Song court is trapped at Yashan. Lu Huaizhou, a general fighting the Yuan, and Zhao Qingwu, a blind woman of mysterious origins, discover a dynastic jade seal concealing the Map of China and the Barbarians beneath the Qiantang River. Blood reveals its mountains and rivers; salt exposes its military defenses. It also mirrors the Mongol navy’s invasion route. Following the Song-era lock foundations, shipwrecks, and firearm debris left behind by the canal gangs, the pair uncover a conspiracy meticulously planned over twenty years by Han Ping, a powerful official and Privy Council envoy. This man, with a flame tattoo of the Manichaean faith behind his ear, has used gunpowder recipes from the Wujing Zongyao and Persian ironworking techniques to turn the Song army’s armor and warships into weapons for slaughtering Han soldiers.

As the rosters of civilians and soldiers killed in the Changzhou massacre, the Yangzhou method for refining fierce-fire oil, and the Fujian recipe for poisoned fire caltrops come to light, Lu and Zhao gradually approach a horrifying truth: Han Ping has used Wen Tianxiang’s Song of Righteousness as bait, while hiding a surrender petition written in ’Phags-pa script aboard the young emperor’s dragon boat. He intends to use the Battle of Yashan to turn a hundred thousand Song soldiers into “human weapons of fire.” On the night of the final battle, amid coral reefs piled with shipwrecks, cast-iron thunderclap bombs unleash a rain of caltrops soaked in aconite poison. As the dynastic jade seal splits into twelve pieces and sinks into the South China Sea, Lu Huaizhou’s Li Quan spear and Zhao Qingwu’s soft sword, patterned after the Yellow River Map, trace the lost score of Moon over Juejiang from the Deyou era across the gilded armor of the Dragon Guard. It turns out to be the very score that Lu Xiufu carried with him before leaping into the sea with the young emperor…