Julia gives birth to a son after she is sent to the penitentiary for the murder of her lover. Fellow inmate Marta becomes her ally, while her mother Sofia is her opponent. As Marta attempts to teach Julia how to be a mother in the least appropriate place, her mother attempts to gain custody so the child can grow up outside of prison. The duel between Julia and her mother expresses the dilemma of what is better for the child, life with his mother in prison, or without her, but in freedom.