Désiré Le Sec has just won the "amateur policeman contest" and he is so glad he 's telling all the people around.He is an insure agent ,and his boss,his uncle,is annoyed :a man took out a big life insurance and died soon afterward.So the nephew is given the responsibility of carrying out an inquiry in the widow's gloomy castle. Playing the occasional private eye is no picnic,mainly when the not-so-merry widow ,then the guests ,die one by one .....Who is doing away with them?Wrong tracks,hidden messages,blowpipes and curare,hanging ....and then there were two,the detective and the last guest..