In a time of turmoil, Yunzhou stands on the brink of destruction. Lin Ye, a shrewd street merchant with a kind heart, partners with the skilled Su Wan to establish a business in the city. Liu Ruyan of Tingxue Tower and the battle-hardened Xiao Sandao each carry their own pasts, brought together here by fate. As local tyrants collude with foreign enemies, the threat of a massacre looms. When disaster strikes, everyone sets aside personal gain. Lin Ye spends his entire fortune to fortify the city defenses, Su Wan strategizes to repel the enemy, Liu Ruyan draws her sword to break the deadlock, and Xiao Sandao holds the city walls to the death. There is no prince or lord to save them—only ordinary people, selfish yet loyal, who stand together to protect Yunzhou with their flesh and blood. A merchant's abacus can also weigh the fate of the people; a swordsman's blade is drawn only to safeguard countless homes.