On a Friday evening, just before closing time Alain Coste is in his office and gets ready to leave, Claire, his PA, manages to stall him a couple of minutes, he goes out and she steals his keys just before he comes back for his jacket.
It is clear that she is preparing a surprise birthday party for Alain, her daughter Louise is there with her boyfriend Henry helping in the kitchen.
Georges assures him that nothing is wrong with him and gives him back his keys to a chalet Alain owns in the nearby mountains, which he used for a romantic escapade.
Meanwhile, in his office Alain has a sudden spasm and begins dictating his ever growing symptoms in his recorder, he leaves the office (which Claire reports to Cécile, who has been keeping a record of all his comings and goings) and goes to the park where he meets Louise, who tells her father that Henry dumped her because she cheated on him.
Manise asks Cécile to check the bank accounts for unusual charges, she does so despite Claire's warnings that Alain shall notice, they find nothing.
Alain sits at his desk and notices that things are not exactly where he left them and asks Claire to retrieve his newspaper, which he forgot at the bar.
Manise however, notices that Alain is close by and makes it look as if Cécile is having an affair with him and asks her to take him to the police station.
Manise also reveals that Agnès is addicted to drugs and that the day of the party she fainted due to withdrawal syndrome.
The next day Cécile drops Alain at the train station but he comes out a few seconds later to take a taxi, however Manise is still tailing him.
As he gets an anesthetic shot from Georges' nurse who turns out to be the lover that he took to the chalet, looks out the window and sees Manise talking to Dr. Colinet in the parking lot.
As Cécile is about to enter the school where she works, Manise tells her that Alain did not take the train to Paris and ventures that he is probably in a hotel with someone else.
When she arrives the anaesthetic has kicked in and Alain lies unconscious in the middle of the field, Claire manages to wake him up.
Alain and Claire go to the police but see Manise and Dr. Colinet walking out of the station together and conclude that they are together in the plot with his wife.
She tells him that he must do something, but by then his paranoia has kicked in and he has begun adding up facts into a big scheme to kill him, which also involves his children, based on the song that they sang to him at his birthday and the changes that they made to fit him (the song involves the story of a poor boy who has to steal flowers for his dying mother in the hospital, only to find that when he finally arrives, she is already dead), Alain changes his will again: all goes to Claire.
Cécile confronts Georges about the truth related to her husband's whereabouts but he does not betray anything and acts surprised when she tells him that Alain is not in Paris.
The film's tableau of duplicity and innocent schemes gone awry is shadowed by the grim business of On the Run and the swelling pathos of After the Life.
[6] Jamie Russell from BBC wrote that "In the best tradition of madcap comedy, the craziness eventually reaches insane asylum levels as straitjackets and sedatives are wheeled out to cope with the manic events.
Alain (Francois Morel) runs a small hi-tech engineering company; he is married to teacher Cecile, and they seem to be a blissfully happy couple.
But Alain has come to the conclusion that he's terminally ill. A chronic worrier, he's convinced that some minor symptoms which he's experiencing are the beginning of the end.