"La Voz de su Amo" is a contemporary film noire set in Bilbao in 1980, an environment marked by corruption and terrorism. The lead character is Charlie, a taciturn individual in his thirties. He works as the trusted man of Mr. Oliveira, an entrepreneur of Portuguese origin who engages in dark businesses. Alarmed by a series of threats and attempts on people's lives, Oliveira decides to put his teenage daughter, Marta, under Charlie's protection. From that moment on, everything becomes complicated: love appears without prior warning, violence generates more violence, friends turn out not to be what they seemed to be and money changes hands.