A dying mob boss hands over his business to an old friend, Fernand. The boss' assistants want to get rid of the latter. But are the Volfoni brothers and Théo real threats? Ensuing fights and shootouts are more comical than deadly.
Ex-gangster Fernand (Lino Ventura) receives a call from a dying friend, a mob boss nicknamed "The Mexican". The doomed mobster talks Fernand into taking care of some criminal business and looking after his soon-to-be-married daughter. When a longtime mobster heavy, Volfoni takes exception to Fernand for being an outsider, they come after Fernand who is equal to the task. He defends himself in a series of comical killings from the onslaught of the mob.—Anonymous
A Public Works Plant in Montauban, in the South-East of France. Late in the evening, the boss, Fernand Naudin (Lino Ventura), takes his car to go to Paris on some urgent matter. Which bothers his assistant because of the annual Fair on the next week-end.
Early in the morning, Fernand arrives in Paris on the Champs-Elysées, to meet his old friend, Louis (Jacques Dumesnil), who just came back from Mexico, where he had gone fifteen years before, to get away from French justice. They remained very close friends, even after Fernand change to legal business. The meeting place is a bowling alley, where Fernand is met by another friend of Louis, Henri (Paul Mercey), the manager of the place.
In an apartment above the bowling alley, Louis is lying in bed, where a doctor is giving him a shot. After the doctor is gone, Louis explains Fernand that he is very ill, and that he came back to France do die and be buried next to his parents. He also tells Fernand about his 18-year old daughter, Patricia, whose mother was a hooker friend of him, and whom he would like Fernand to take care of after his death. Money is no problem, since Louis has several not quite legal business, but which work very smoothly, and which get enough money for Patricia's needs. Nevertheless Fernand is not very happy about the idea.
Their heated conversation is stopped by the arrival of Louis' assistants, Raoul (Bertrand Blier) and Paul (Jean Lefebvre) Volfoni, who run a clandestine and illegal roulette on a barge, and Théo (Horst Frank), who runs an illegal distillery. Théo, who is homosexual, has come with his boyfriend, Vincent (Georges Nojaroff), whom Louis doesn't want to be present. Louis tells the three remaining men that Fernand is now in charge of his business, which doesn't seem to please Raoul Volfoni. But Pascal (Valentino Venantini), Louis' gunman, being around, neither the Volfoni brothers nor Théo don't say much about it.
After they're gone, Fernand remains alone with Louis. When Louis has an attack, Fernand calls Pascal to help him and Louis dies in both men's arms.
After Louis' death, Fernand goes back in the bowling alley, where Henri gets him something to eat. The Volfoni brothers try to talk Fernand out of taking over Louis' business, but Fernand refuses not to keep a promise made to a dying friend. Their conversation is interrupted by a phone call from Tomate, who runs a illegal roulette in a farm. Tomate seems to have some problem with nervous patrons. Pascal wants to have a look and Fernand asks him to go with him. After their departure, Théo, who, unlike the Volfoni, didn't say a word to Fernand, tells Vincent, his boyfriend, that he has just taken care of Fernand as a problem.
Pascal and Fernand reach the farm, but they've just left their car when they get machine-gunned from a gunman in a big American car. Pascal kills both the gunman and the driver, and then goes inside the farm, followed by a slightly disturbed Fernand, who wonders if the Volfoni are not the sponsors of the dead gunman. Pascal agrees with him.
Tomate (Charles Régnier), alone in the roulette room, seems very surprised by what Pascal and Fernand tell him. He sends his henchman, Freddy (Henri Cogan), to clean the mess made by the gun fight, and then he explains to Fernand that he had no problem that evening in the roulette room, and consequently that he never phoned the bowling alley. But when Fernand phones the bowling alley, he learns that Henri has been shot and killed, and that the police is already there.
Pascal drives Fernand to the 18th century manor that Louis had bought for his daughter, who lives there with her two «uncles», Folace (Francis Blanche), who is a shady attorney in charge of Louis' business, and Jean (Robert Dalban), who is a former burglar, adopted by Louis, and converted into a butler. Pascal goes back home and Folace explains to Fernand that Patricia is a bit of a problem, because she consistently gets kicked out of every private school she goes to. Fernand, who wants to get back to Montauban as soon as possible, tells Folace that he is going to make Patricia understand how she must behave. Folace also tells Jean and Fernand that Patricia must never know that her father, whom she knows only through his letters, is dead.
Next morning, Fernand is shaving when Patricia (Sabine Sinjen) enters the bathroom. She teases Fernand, whom her father, in his letters, describes as some sort of modern knight. When Fernand tells her they must have a serious conversation, she gets away.
A bit later, Folace tells Fernand that Louis' business is not running as smoothly as he thought, and even less since Louis' «assistants» learned about his death.
Fernand then meets Patricia's fiancé, Antoine Delafoy (Claude Rich), a musical genius or so he pretends himself to be ! Actually he is a very smart young man, a bit eccentric, and who keeps on talking all the time, to Fernand's obvious annoyance.
Pascal discreetly interrupts Fernand's conversation with Antoine, to tell him that Louis' «assistants» are holding a secret meeting on the Volfoni's barge. Fernand feels like going to see what it's all about, along with the very efficient Pascal. Antoine doesn't believe in Fernand's unexpected board meeting, and thinks Fernand is going to meet some girl !
Around the roulette table inside the barge, are gathered the Volfoni brothers, Théo, Vincent, Tomate, Freddy, and Madame Mado (Dominique Davray) who runs an illegal brothel. Raoul is trying to get them to do something about the situation, but Théo objects that, since Louis' death, there have been too many murders around.
On the barge deck, Fernand, Pascal and Folace are met by Léo, who is the barge «official» skipper. When Léo says he wants to ask the Volfoni before letting his visitors inside the barge, Fernand punches him and sends him into the river.
In the roulette room, the meeting is very heated, when someone knocks at the door. Freddy opens the door and gets Fernand's fist in his face. Pascal walks in behind Fernand with a gun in each hand. Bastien (Marc Ronay), Volfoni's gunman, wants to react, but Raoul stops him.
Fernand sits down, and, with the help of Folace, goes on with important matters. He asks Mado about the irregular management of her brothel. She defends her business with quite a sense of humor. Fernand turns to Théo, who talks about his problems with illegal alcohol.
Meanwhile, in a small room near the entrance of the roulette room, the two gunmen, Pascal and Bastien, are talking shop and showing each other's guns.
After Théo's, Fernand opens the Volfoni's file. He explains he has decided to make their bookkeeping much easier : he will just ask them to pay this year what they paid the year before. He then asks Pascal to come and get their money during the coming week.
Fernand and friends leave the room with Bastien. After they've gone, Mado makes fun of Raoul, whom she finds a bit of a coward. Raoul gets very angry when she says that. Then someone knocks at the door and he crosses the room to open it. He gets Fernand's fist in his face. Fernand tells him that he gives him an extra ten percent on his debt because of the delay.
Back to the manor, Fernand finds Patricia and Antoine seated close to each other on a sofa, listening to Corelli in the dark. He sends Patricia to her room and Antoine out of the house.
Later in the evening, Fernand is listening to the Corelli record while eating some chicken, when Pascal and Bastien enter discreetly through a French window. The two gunmen explain to Fernand that they've found they are related, and the dispute between Fernand and the Volfoni is giving them a moral dilemma. They are afraid that, one day, they will have to face each other, guns in hand. So Bastien has just resigned his job with the Volfoni and Pascal is doing the same with Fernand.
A few days later, Fernand is reading a dissertation Patricia wrote about Corneille, Racine, Bossuet and Pascal. He finds it so good that he thinks that the teacher could have given her a higher grade. He is interrupted by a call from one of his assistants in Montauban.
A few moments later, Folace explains to Fernand that the expected money didn't come in when he gets interrupted by a call from Raoul, who tells him there are some problem at the distillery.
At the distillery, Tomate asks Théo if he thinks Fernand believed what they suggested the too naïve Raoul to tell him. The answer is the noise made by Fernand's car arriving at the distillery. Théo explains to Tomate and Freddy that, after they get rid of Fernand, they will just have to get also rid of the Volfoni brothers, and then they will be the only bosses of the late Louis' business.
After he has sent his assistants on their duties, Théo greets Fernand with a feigned surprise. He explains to Fernand that his problem is that he just lost the driver who was supposed to drive a truck full of moonshine (illegal alcohol), and because he, Théo, doesn't have a driver's license anymore, he asked Raoul to get him a new driver. Fernand tells him he is going to drive the truck himself.
To reach the «meeting place», Fernand has to cross the Fontainebleau forest. This is where Théo and Tomate are waiting for him with a machine-gun. They shoot the truck, which gets off the road, and then starts burning. Fernand succeeds in leaving the truck, and with a burned and torn suit, he reaches the Volfoni barge.
There, he knocks Raoul out, and then empty the open safe. Paul Volfoni, who does not understand a word of what Fernand tells him about trucks and moonshine, nevertheless lets the very angry Fernand takes the money out of the safe.
When Fernand gets back at the manor with his bag full of money, it is to find that his «niece» Patricia is having a party where she invited a lot of young idle «bourgeois». Many sport cars are parked in front of the manor. When one of the owners of one of these sport cars says something quite inappropriate about the relationship between Patricia and Antoine, Fernand feels he has to give the young guy a good thrashing.
He then enters the manor, where all the young guests are dancing while Jean is moving around them with a tray full of drinks. Fernand has a little chat with Patricia, and then goes to the kitchen.
In the kitchen, Folace is buttering toasts for the guests. Fernand shows him the money inside the bag. When Jean sees Fernand torn suit, and when Fernand tells him it is the work of the Volfoni, Jean puts a gun in his pocket.
A quite useful decision when, a few minutes later, the Volfoni brothers enter the manor. Jean guide them to the kitchen, where they get in, gun in hand. Jean comes in behind them, pointing his own gun in their backs, and he asks them to give him their guns. Paul, to calm the situation down, start buttering the toasts. A very drunk girl enters the kitchen, because she is looking for a drink. When she takes some money in the bag to buy drinks, Folace is so aggressive with her that she goes out very quickly.
Raoul says he would like very much to share a drink with his friends, but Folace tells him that the kid have drunk everything in the house, and that the only bottle left is an old bottle of moonshine whisky. Even those tough men find it a bit strange to drink, and get drunk very quickly.
Meanwhile, Antoine is telling Patricia he feels like telling «uncle Fernand» about their love.
Back in the kitchen, all the men are completely drunk. Raoul feels like visiting the bathroom very urgently, and rushes out of the kitchen.
When Raoul goes out of the bathroom, he feels better, even though he is still drunk, and he starts flirting with Patricia, offering to give her a «job» in Egypt. Patricia knows very well what kind of a job he means, but Antoine doesn't find it very funny.
Back in the kitchen, Raoul tells Fernand about the «inappropriate» jealousy of Antoine, and Fernand decides it is time to close the shop.
Helped by the Volfoni brothers and Folace, Fernand kicks all the guests out of the house. The men are so excited by their job that they even kick Paul Volfoni out, which makes them laugh a lot. But they stop laughing when they see Patricia crying on the staircase.
Next morning, Folace wakes up Fernand to tell him that Patricia has gone away during the night with her suitcase. Fortunately, Jean wrote down the license plate of the taxicab who took her away.
The cab driver brings Fernand to Antoine's apartment. When Fernand walks in the living-room, Antoine is experimenting «musique concrète» (concrete music). He doesn't seem to appreciate Fernand interrupting him. But Patricia calms Fernand down when she walks in from the kitchen. She tells her «uncle» she is going to marry Antoine. Fernand likes the idea better when she tells him that Antoine's father is vice-president of the International Monetary Fund.
Two or three days later, it is Fernand's birthday. Early in the morning, Patricia, Jean and Folace give him a present each. Patricia adds a present brought in very early from the Volfoni brothers. When Fernand hears a threatening tick-tock coming from the parcel, he throws it through the open window, and the parcel explodes in the garden. We can see Théo and Vincent walking discreetly away.
Fernand goes to the Volfoni's barge, and, when Raoul opens the door, Fernand sings «Happy Birthday» and then punches Raoul violently on the nose. After his departure, Raoul fixes a small bomb to get his own back on Fernand.
During the night, Fernand hears a strange noise and puts a gun in his night-robe pocket.
Meanwhile in the garage, Raoul is putting his bomb inside Fernand's car. He sends his brother away to check on the surroundings, and after Paul's departure, Fernand walks discreetly in the garage.
After Fernand has «taken care» of Raoul, we find the latter in an hospital room, covered with bandages and plaster casts.
Fernand's «accident» with the truck full of moonshine is in the newspapers' front page. But Pascal and Bastien tells Fernand it was wrong of him to think it was the Volfoni's fault. They explain that, if the Volfoni had decided to kill Fernand or Henri, the first person they would have asked to do it would have been Bastien, their official gunman. Pascal thinks the whole business comes from Théo. Fernand asks Pascal and Bastien to go and have a friendly chat with Théo.
In the distlllery, Pascal and Bastien do not find Théo, but only Tomate. They make him talk and then kill him. When he finds Tomate's body, Théo understands he is next on their list, and he decides to take care of Fernand before Fernand takes care of him.
Théo, Vincent and Freddy try to storm the manor, but Folace, Jean and Fernand don't let them do it and fight back. In the middle of a gunfight that looks like something out of a Western movie, Amédée Delafoy (Pierre Bertin), Antoine's father, crosses the park to ask «Uncle Fernand» the hand of his «niece» Patricia for his son. The gunfight goes on, but, because Amédée is deaf as a doorpost, he doesn't hear a thing ! He begins to have a feeling that something may be wrong when a bullet hits the ceiling above him and he gets covered with plaster ! The gunfight stops with the arrival of Pascal and Bastien. Théo thinks that, with two marksmen on the other side, the fight is not fair anymore.
To take his own back for his defeat, Théo waits for Raoul coming out of the hospital along with his brother, and shoots them. Both Raoul and Paul Volfoni are back in an hospital room, both covered with bandages and plaster casts !
A few days later, Fernand is getting his «niece» married. He is wearing a frock coat and has a quiet chat with the bridegroom, Antoine, when Pascal comes in discreetly to warn him that Théo is leaving the distillery with his friends. Fernand asks Jean and Folace to take care of the guests while he is going to take care of Théo with Pascal and Bastien, who is waiting for them at the distillery.
At the distillery, Théo and Freddy are sorting out important or incriminating documents, which Théo puts inside a bag. When Vincent comes in to tell them about Fernand's arrival, they take their weapons to give Fernand a warm welcome.
The first to die is Vincent, burned to death by a jerry can full of gasoline, set on fire by Bastien. Next comes Freddy, who, after a long fistfight with Fernand, breaks through a brick wall on the first floor of the building down to the ground.
Théo succeeds in escaping with his car. But Pascal prevents Fernand from running after him, because it is almost wedding time. Pascal and Bastien help Fernand to fix his frock coat, a bit torn during the fight, and bring him in front of the church just when Folace was starting to think he would never see him.
While the service is going on inside the church, Théo parks in front of the church, and gets his machine-gun ready for Fernand and guests when they walk out of the church.
Inside the church, every one is listening to the organ and choral music, when they hear a loud blast coming from outside the church. They all turn their heads toward the door, through which Pascal and Bastien walk in very quietly, and make a respectful sign of the cross.
The last scene of the film shows Théo's car burning in front of the church with Théo inside the car !