Nick Moran stars in this drama as Christie Malry, a lowly bank worker who indulges in extreme fantasies of sex and violence to escape his humdrum life of a job he hates and having to care for his dying mother. Whilst taking an evening class, Christie learns the principles of double-entry bookkeeping and adopts the theory that for every credit there must be a debit for his own life. Soon enough he uses these 'credits' to avenge those he feels have wronged him, and these acts of revenge rapidly get out of hand. Set against this is the equally interesting story of Pacioli, the monk who invented double-entry bookkeeping in Renaissance Italy.