It conveys the thoughts and memories of Mosén Millán, a Catholic parish priest, as he sits in the vestry of a church in a nameless Aragonese village, preparing to conduct a requiem mass to celebrate the life of a young peasant named Paco killed by the Nationalist army a year earlier, at the outbreak of the Spanish Civil War.

As he waits, his thoughts are interrupted by the occasional comings and goings of an altar boy, who hums to himself an anonymous ballad.

In the present, Millán, fatigued, prays as he awaits the requiem mass with recollections of Paco's life.

The altar boy comes and goes and both remark on the lack of people attending mass.

Millán, feeling guilty knowing that he played a role in Paco's death, asks the altar boy to leave the church to look for mass attenders in the town square when the altar boy sings the parts of the ballad that refer to Millán.