In Pamplona, Spain, at the time of the running of the bulls (which takes place during the festival of San Fermin), a pious surgeon who belongs to Opus Dei (a Catholic service organization) tries to ward off the temptations of a lusty nurse by attending Mass frequently and clutching his crucifix. Finally, unable to resist further, he succumbs.
Guilt-ridden, on the advice of his priest, he runs off, leaving both the nurse and his secretly unfaithful wife behind.