Everyone in the capital mocks the Old Madam of the Duke of Ning's Mansion for being illiterate, failing to manage the household, and only knowing how to hold a cat and bask in the sun. After granddaughter Shen Mingyun marries into the East Palace, she is secretly plotted against by Concubine Lin Wan, and her natal family's second branch is incriminated for embezzling military provisions. To protect her grandmother, Shen Mingyun studies court affairs bitterly and investigates account books, gradually securing her footing. At the Mid-Autumn palace banquet, Lin Wan sets a trap to make the Old Madam make a fool of herself in public, attempting to hollow out the Duke's Mansion. Who would have expected the Old Madam to walk into the hall leaning on her staff, uncovering a thirty-two-year-old old ledger and pulling out an imperial decree from the late Emperor cherished for many years, shocking the entire court! It turns out she hid her edge for forty years, solely to protect her granddaughter's lifelong peace.