This is the (funny) story of four Roma traffic police agents in the 1950s. Their lives are crossed in affairs that often go beyond mere job relationships. 'Guardia scelta' (special agent) Giuseppe, an aspiring composer, wants to write an anthem for the Roman traffic police. 'Guardia' (agent) Alberto Randolfi has a too-strong inclination to fine everyone and is dreaming about learning French. 'Brigadiere' (sergeant) Pietro Spaziali is busy looking after his little son Tonino and daughter Maria who is engaged to marry a boxer. The 'Maresciallo' (Marshal) tries to manage and solve all the troubles they attract.