Action adventure film in which a masked vigilante by the name of Diego de la Vega (Alain Delon) sets out to seek vengeance after his old acquaintance Miguel de la Serna (Marino Masé) is murdered before he can take up the position of governor of Nueva Aragón. Vega learns that Nueva Aragón is rife with corruption and is soon to be ruled by the greedy Colonel Huerta (Stanley Baker), who ordered the assassination of Serna. Vega creates an alter ago by the name of Zorro based on a legendary tale told in the streets of Nueva Aragón, and uses this character as a means of privately executing his revenge.