This is the (funny) story of four agents of Roma traffic police in the '50s. Their life are crossed in affairs that often retire from mere job relationships. 'Guardia scelta' (special agent) Giuseppe tries to be a composer, he wants to write the 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 at his little son Tonino and daughter Maria who is going to marry a boxer. The 'Maresciallo' (Marshal) tries to manage and solve all the troubles they often do.