Paolo, a skilled mechanic in a modler's factory in Italy, defends his friend Brocco, when the latter is discharged and incurs the foreman's enmity. The treacherous Brocco steals an empty six-pound shell, which Paolo treasures as a relic of the war, and makes a bomb, with which he wrecks the modler's factory. A piece of the bomb which bears Paola's name is found and on this evidence the innocent man is sent to prison for five years.