A product manager dies suddenly and wakes up in a Northern Song prison. No System, no wise old mentor. Using elementary-school math, he exposes the jailer's embezzlement and earns himself his first meal of meat and wine. From distilled liquor and double-entry bookkeeping to military bonds and border outposts, he uses modern knowledge to weave a safety net in a flourishing age on the verge of collapse, saving himself and a group of people who should never have been crushed by their era. At his side is a woman from Yanzhou, three knives at her waist and a ledger in her hand, filled with her father's final words.
