The young Loris is undergoing a trial for killing his girlfriend Maria Luce. According to the reconstruction of the facts, the young man would shoot his mistress making it then end up under the wheels of a tram. On the remains of the woman's body, however, there is no trace of a gunshot wound and, during the trial, the accused, who appears hypnotized, refuses to answer. The arrival of the ex-lawyer Cidoni, who takes the place of the defense, overturns the thesis of the prosecution and instead demonstrates that the victim was not a naive girl as had been believed up to then.