The film opens with a prologue that consists of four segments described by critics as "vignettes". They show the principal characters in different parts of the world and provide their backstories.Part I: PrologueVignette #1: Veracruz, MexicoNilo (Francisco Rabal), an elegantly dressed man, enters a flat in Veracruz. He immediately executes the unassuming tenant with a silenced pistol and proceeds to casually walk out onto the square.Vignette #2: Jerusalem, IsraelA group of Arab terrorists disguised as Jews causes an explosion in the city and flee to their hideout, where they equip weapons and plan their escape. After being surrounded by the military, they split up; two are killed and one apprehended. The only one who manages to escape is Kassem (Amidou). The segment ends as he helplessly stares at his captured companion.Vignette #3: Paris, FranceWhile discussing a book his wife is editing, Victor Manzon (Bruno Cremer) discovers an anniversary gift from her: a watch with a special dedication. After meeting with the president of the Paris Stock Exchange, where he is accused of fraud, Victor is given 24 hours to make amends. Victor meets his business partner, Pascal, and they quarrel; Victor insists that Pascal contact his father for assistance. Victor dines with his wife and her friend in a glamorous restaurant, and, he later receives a message from a butler that Pascal is waiting for him outside. When he learns that Pascal's father has refused to help, Victor is adamant that they try again. He walks his partner to a car, but Pascal shocks Victor by committing suicide. Faced with impending doom, Victor leaves both his country and wife.Vignette #4: Elizabeth, New Jersey, USAAn Irish gang robs a church with rival connections in Elizabeth that organizes bingo games, and they shoot one of the priests. Back in their car, the gang members have a violent argument that causes Jackie Scanlon (Roy Scheider), the driver, to lose concentration and collide with a truck. Everyone is killed but Scanlon, who is heavily wounded. The wounded priest turns out to be the brother of Carlo Ricci, a mafia leader who also controlled the flow of money in the church and now wants to kill Scanlon at all costs. Jackie meets with his friend Vinnie, who reveals his fate to him and finds him a suitable place to escape. Jackie has no choice but to agree.Part II: Life in PorvenirKassem, Victor and Jackie all assume fake identities and end up in Porvenir, a remote village in South America. Its conditions provide a stark contrast to their previous lives. The village economy is heavily reliant on an American oil company. Kassem befriends a man called 'Marquez', presumably a Nazi veteran. They all live in extreme poverty and earn meager salaries. All want out, but their savings are inadequate for emigration. After some time, Nilo arrives in the village, raising suspicions. In the meantime, an oil well over 200 miles away explodes, and the only way to extinguish the fire is to use nitroglycerin. Since the dynamite has been improperly stored in a local depot, the nitroglycerin contained inside has become highly unstable, so the faintest vibration could cause an explosion. With all other means ruled out, the only way to transport it is to use trucks. The company seeks four drivers to man two such vehicles. Kassem, Victor, Jackie and 'Marquez' are offered the job, but they have to assemble the trucks using scrap parts. Shortly before their departure, Nilo kills and replaces 'Marquez', which angers Kassem.Part III: JourneyThe four drivers embark upon a perilous journey, facing many hazards and internal conflicts. Despite their differences, they are forced to co-operate. Eventually, only Jackie survives, and, towards the end, he struggles to keep sane, overwhelmed by hallucinations and flashbacks. When his truck's engine dies just two miles short of the destination, he is forced to carry the nitroglycerin on foot.EpilogueScanlon is offered legal citizenship and money, as well as another job, but he declines, opting instead for a dance with a barmaid. As he dances, Carlo Ricci's henchmen, along with his old friend Vinnie, emerge from a taxi and enter the bar. A gunshot can be heard.
Output: Question: Who killed marquez?, Answer: Nilo