"Regina Coeli" is the nickname with which inmates call Regina, voluntary assistant in Rome's Rebibbia jail, very involved in solidarity but lonely in his private life. The jail director entrusts her with the task to try re-educating Graziano, a young Sardinian sentenced for a kidnapping of which he always proclaimed himself to be innocent. Regina is way too much mature and lonely not to feel intrigued by the mysterious personality of the illiterate shepherd, who expresses himself only in his almost unintelligible Sardinian dialect.