西班牙人在南美洲殖民统治时代，苛捐杂税民不聊生。新总督米格尔在上任途中被杀，临死时把官印交与好友“欧洲第一剑士”唐迭戈（阿兰·德龙 Alain Delon 饰），要其承继遗志。三个月后，新总督突然出现，不过他似乎是一个贵族的纨绔子弟，一切事物均假手他人。与此同时，民传说一位蒙面黑侠从天而降，警恶惩奸，锄强扶弱，"佐罗"的英名不径而走，令殖民者大为头痛，而新总督的身份更令人怀疑。身兼总督和侠客双重身份的迭戈与残暴的韦尔塔上校斗志斗勇，终于在韦尔塔强娶奥顿西娅的婚礼上结果了这个恶棍的性命，为当地百姓除了大害。佐罗告别了好姑娘奥顿西娅，告别了新阿拉贡。这个主持公道、追求自由的义侠佐罗又跨上枣红马去行侠仗义了……

Duccio Tessari's rare Giallo starring Helmut Berger, Giancarlo Sbragia, Evelyn Stewart, Silvano Tranquilli & Carole Andre. A young student is murdered in a park by an unseen assailant during a heavy thunderstorm. The murderer makes his escape, but is identified by a number of people at the park exit. A sports presenter from a local TV channel, Alessandro Marchi, is quickly arrested, and despite protestations of innocence, is charged with the murder. Marchi calls his lawyer, who promises to have him released very soon, but when it comes to the trial the lawyers case is a weak one, full of holes, and Marchi is duly found guilty. All is not what it seems and it soon becomes apparent that the lawyer is having an affair with Marchi's wife and obviously does not have Marchi's best interests at heart…