Adémaï is forcibly engaged to the farmer's daughter. He tries in vain to get rid of it and, weary of the struggle, flees in a plane with his comrade Michelet whom he believes to be an instructor. For three days and three nights, the unfortunates turn in a closed circuit, thus beating the world record.

Maigret investigates in Concarneau where the passage of a yellow dog accompanies a series of murders, sowing terror in the population. The police seem helpless. It must be said that it has no significant evidence.