Agaton Sax and the Diamond Thieves (originally published as Agaton Sax och de slipade diamanttjuvarna in 1959; published in English in 1973) is a book about detective Agaton Sax

Agaton Sax

Agaton Sax is the hero of a series of Swedish-language comedic detective novels written for children by Swedish author Nils-Olof Franzén and illustrated by Åke Lewerth. The English edition was illustrated by Quentin Blake....

 by Swedish author Nils-Olof Franzen

Nils-Olof Franzén

Nils Olof Franzén was a Swedish author who wrote the Agaton Sax series. He was born 23 August 1916 in Oxelösund. He died on 24 February 1997 at age 81.He was director of programmes for Swedish Radio from 1956 to 1973, and also wrote a number of biographies....

.

Plot summary

The Koh-Mi-Nor diamond is stolen and a very clever thief is putting messages about it, in a secret code, in the personal column of the newspaper published by the Swedish detective Agaton Sax.