I love de Funés too, but I can't claim to have seen all of his movies; (he made like a hundred, right?) I will say that this one is absolutely hilarious though.
De Funés plays Septime, the despotic owner of a high class Paris restaurant, one which entertains the Paris glitterati as well as ministers of the French government. Once a foreign president disappears in the middle of Septime's grand number of lighting fire to a fancy dessert, Septime finds himself in an escalating drama. The police inspector suspects him, a revolutionary group from the missing president's country is after him, and the president's entourage blames him and demands he helps them find the missing head of state. Everyone is looking for the president, and they all ask of a terrified Septime to find him.
The poor Septime travels effortlessly (and lightning fast) between the sheer horror of finding himself in this situation, and the hilarious fits he throws whenever a staff member of his fails to meet perfection. The catch phrase of the movie is an angry kissing sound Septime makes whenever he wants to call an employee's attention to himself, without disturbing the guests, and it never gets tired.
I once heard a rumour that de Funés in person was exactly like the high-strung choleric characters he played, and thusly passed away too soon in a heart attack. I have no idea if this is true, but you do get the sense that he is more or less playing himself, which makes for some very convincing comedy. The man was a comedic genius, and this movie is a superb vehicle for him.