In a department store, a tailor's counter, a pair of biological siblings, an uncalculable ledger of human favors, and the rules behind a leather tape measure. Old tailor Dong Dehai and his elder sister Dong Guilan guarded the counter together for twenty years, falling out because the contracting fee changed to taking thirty percent of the turnover. Operating separately, digging up old accounts, and calculating conscience accounts, they finally reconciled and established the rule that "business is business, and human favors are human favors."