San Giovanni decollato or Saint John the Baptist's head on a platter, was a common religious motif from the Middle Ages on, parodied in the film's poster.

In a town, near Naples, in 1900, the cobbler Agostino Miciacio is accused by tenants of his apartment building to be crazy.

He is very devoted to John the Baptist, so Agostino lights a candle every night in a small chapel in the courtyard.

Meanwhile, Agostino, in addition to following the case of oil stolen, must fight against the daughter Serafina who has fallen in love with a poor young lamplighter.

But he also has to fight against his wife Concetta, authoritative and cruel woman, so he hopes that St. John makes a grace for him, taking away her voice.