The Sleeping Voice is a drama set during Spain's post-civil war period. Pepita, the film's protagonist, is a young woman who works in a rural area of Huelva, and decides to move to Madrid to be near her sister Hortensia. Hortensia has been imprisoned, and is facing the possibility of a death sentence.
While in Madrid, Pepita becomes involved with a group of women who are fighting against Franco's regime. The women are political prisoners who are being held in a nearby prison. Pepita is initially hesitant to get involved with the group, but she is eventually drawn into their cause.
As she learns more about the women and their struggles, Pepita becomes more determined to help them. She begins to use her relationships with prison officials to gain access to the women, and starts to smuggle messages in and out of the prison.
The film explores the themes of political activism, sisterhood, and the dangerous world of Franco's Spain. It is a moving and powerful story of hope and resistance in the face of oppression.