Knock (original title Knock[1]) is a French comedy film from 1951, directed by Guy Lefranc, written by Georges Neveux, and starring Louis Jouvet.

The movie is based on the 1923 theatre play Knock ou le Triomphe de la médecine (Knock or The Triumph of Medicine) by Jules Romains.

Knock arrives in the country village Saint-Maurice to succeed Dr. Parpalaid, an honest man whose patients are rare.

Knock sets about convincing everyone that a healthy person is someone who doesn't know how sick he is.

As a result, the whole village takes to bed, the hotel is transformed into a clinic, and even Dr. Parpalaid, who temporarily returns to his village, is so worried about his health following the "diagnosis" of Dr.