The film begins in the stormy period of 1962, France, where an assassination plot is attempted on Colonel Charles de Gaulle, the French President. De Gaulle had granted the country of Algeria independence, a decision that enraged many French citizens. Many of them, mostly fanatics and extremists from the army, forced an underground organization called the OAS, which put the plot in place. As the Presidents car passes by a group of OAS agents, headed by Jean-Marie Bastien-Thiery, open fire on the vehicle; a number of bullets shatter and enter the vehicle, but not a single of them make a mark on de Gaulle. Six months later, Bastien-Thiery and the other members involved in the plot are captured and executed.
The top members of the OAS Colonel Rodin, manager Casson and treasurer Montclair take stock, and realize that they cannot make any move as they will constantly be watched and identified: the OAS is planted with informers who will watch every members move, and each member has had their complete details archived. Rodin realizes that what they need is a foreigner, someone whom no one in France has seen and has no record.
Three months later, Rodin has succeeded in finding the right individual, an Englishman with a short but impeccable record. He invites him to Vienna for an interview by the three OAS leaders. The Englishman is smart, enigmatic and cold-blooded; he points out the need for an outsider to assassinate de Gaulle, given that the other attempt failed and that informers within the OAS have crippled the organization. He accepts the job, but asks a fee of half a million US dollars (a huge sum back then), citing the targets first-class security and that the job is an once-in-a-lifetime assignment and certainly to be his last. He demands utmost secrecy and anonymity, and asks that no one but the four of them know of this project and that he work completely by himself. He takes the codename the Jackal, and takes his leave of the OAS heads; his farewell is observed by Rodins bodyguard and adjutant Victor Wolenski.
The Jackal begins his preparations: he researches extensively on his target, he acquires two false passports, he pays a visit to Paris to acquire a good shooting location, and he contacts two individuals in Belgium. The first is an armorer whom he commissions to build a special rifle; the second is a forger from whom he requires special French documents.
Later on, the Jackal receives an OAS contact named Valmy that will inform him of any developments regarding the President (around the same time the OAS send a female agent named Denise to bed a high-ranking French politician). Two weeks after visiting the armorer and forger, he returns to acquire his purchases. He is satisfied with the gun the armorer has made, and a trial of the rifle goes well; the forger on the other hand tries to blackmail him over his papers, and the Jackal snaps his neck.
All his plans complete, he leaves for France under the name of Paul Oliver Duggan.
Meanwhile, to raise money for the Jackals fee the OAS carries out various bank robberies across France. This sudden crime wave is noticed by the French Action Service (the French espionage branch), and their suspicions grow when they learn that Rodin and his associates have suddenly secluded themselves in a hotel room in Rome. They observe that they are being attended to by Wolenski; they presently abduct him and bring him to Paris. They interrogate and torture him to death, but all they get is that a blond killer named Jackal visited his superiors. This however is enough to deduce that this Jackal has been contracted to shoot the President of France.
The French Interior Minister asks for an interview with the President, but his demand for secrecy is rebuffed; de Gaulle is a proud man who refuses to go into hiding or shield himself. The Interior Minister instead convenes a secret council to deal with the Jackal, which includes high-ranking individuals like Police Commissioner Berthier and Colonel St-Clair. Berthier states that because of the Jackals anonymity from even his own employers, no one has a clue where to start looking for him; the key to finding and stopping the Jackal thus is to establish his identity. He recommends his own deputy, Inspector Claude Lebel, as the best detective in France and ideal for the job of uncovering the Jackal.
Lebel, a mild-mannered but tenacious policeman, is summoned to the council. He is given access to every resource available, but he is asked to keep things secret, and that he succeeds. Lebel brings in his assistant Caron to help him out, and the two get to work contacting the heads of police agencies abroad. Meanwhile, St-Clair arrives home and pours out everything about the situation to his mistress, Denise. She later slips off and phones Valmy...
Over in London, enquiries are being headed by Inspector Thomas, who has been given express authority by the Prime Minister to make full investigations regarding the Jackal (ensuring that he not be English, or if he is to be stopped). The British police come up with two things that they pass over to Lebel. Firstly, that there was a suspicious character named Charles Calthrop who was in the Dominican Republic around the time its dictator Trujillo was assassinated (Jackal in French is chacal, the word formed from the first three letters of each name); a search on Calthrops home reveals he is absent. Second and more worryingly, a review of all passport applications reveals that one was made for Paul Oliver Duggan, who had died at the age of two.
Meanwhile, the Jackal learns from Valmy that his assignment is blown, but decides to continue on regardless. He makes it to a hotel at Grasse, where he spends the night charming and seducing a fellow guest, Baroness Collette de Montpellier.
The next morning the hotel records are taken and scanned, as is French custom (and more urgently than usual). Presently Duggans name is spotted and immediately Lebel orders forces on the hotel and he heads over there himself. They find no sign of the Jackal, him having already left the hotel (something Lebel finds strange), but they learn that the Baronesss bed had been slept in by two people. Lebel interviews the Baroness, but she denies knowing a thing about the man.
The Jackals quick getaway before the police arrive is cut short by accidentally crashing his car. He decides to head for the Baronesss estate, where she takes him in. That night she tells him the police were looking for him, but promises she wont say anything if he tells her what hes about; in response, he strangles her. He takes on a new disguise and identity of bespectacled Danish pastor Per Lundqvist, and quickly but quietly leaves. He heads to Tulle station in the Baronesss car and catches a train to Paris. Hours later, the servants discover the Baronesss body.
Lebel reports the failure of catching the Jackal and the murder of Madame de Montpellier, and notes that he could not have escaped unless he had been forewarned and that he now has the identity of a Danish pastor (having traced the car to the station and questioned the station authorities). He also notes that the murder means he can do away with secrecy and initiate a public manhunt. A police squad heads to Paris station to intercept the Jackal, but they arrive a few minutes too late. Lebel sends police to check every hotel in Paris, but the Jackal evades them by entering a Turkish bathhouse and being picked up by a French homosexual.
Lebel uses a phone tap to discern that Denise is the OAS spy thats been tipping off the Jackal. He presents a recording of her phone call to the council, and St-Clair leaves (he later commits suicide); hed tapped all the phones of the council members, having had suspicions about the Jackal being forewarned. Afterwards, he works out that the Jackal will strike in two days, or August 25 1963 Liberation Day, the anniversary of when France was freed from Nazi Germany. De Gaulle, as a World War 2 veteran, is sure to make a public appearance on that day, and the council disbands, intending to make all attempts to find the Jackal before then.
Meanwhile, the Jackal kills the homosexual when he sees a public broadcast about Per Lundqvist being wanted for murder.
In the early hours of Liberation Day, the Minister wearily informs Lebel that they couldnt find the Jackal. All they can do is implement the utmost security precautions around. The day goes on, but nothing happens. Some time later, a police officer allows an old one-legged French war veteran to head to his residential address, after seeing his papers; the Jackal enters his location, sheds his disguise and disassembles his crutch to form his rifle, and waits for the President to present medals to former French Resistance members.
Lebel strolls around looking for anything the least suspicious or out of place, but he doesnt find anything until he meets the police officer around the time the President presents medals. He learns that the officer let a cripple with a crutch through, sees that the address pointed out has a window open on the top floor, and rushes over there, ordering the officer to follow him.
The Jackal aims, takes his shot... and misses. De Gaulle had suddenly bent his head to kiss a Resistance soldier, a French custom. The Jackal reloads his gun for a second shot, but then Lebel and the officer burst in on him. He guns down the officer, but Lebel snatches up the officers submachine gun and empties it into the Jackal.
Over in London, Charles Calthrop appears at his flat. The British authorities take him in for questioning, but conclude that he had nothing at all to do with the Jackal and close the matter (also forswearing any responsibility regarding the Jackal, since he was an Englishman but also a Dane and a Frenchman). Thomas ponders who the Jackal really was...
The film ends with a funeral in Paris: a body is buried in an unmarked grave, with Lebel the only witness.