The Diamond Thieves by Louis Henri Boussenard. Short summary

5 seconds

Three Frenchmen search Africa for the treasure of the Kaffre kings. Bandits pursue the expedition. A gas explosion causes the cave with the treasure and the bandits to fall into the abyss. The friends return home.

1 minute

Three French friends set out to find the treasure of the Kaffre kings in South Africa. One of them, Albert de Villroge, is pursued by an enemy — an unlucky rival with his goons. The friends have to overcome sands, thirst, hunger, fight elephants, lions, crocodiles, slave traders and brigands.

One of the bandits, disguised as a missionary, manages to join a treasure-hunting expedition and steal a treasure map. With a fake letter, the villains lure Albert’s wife out of the house and kidnap her. In the meantime, the Frenchman happily avoids being lynched on false charges and sets out in search of Madame Villeroge.

A fake missionary accidentally finds the diamonds of the Kaffre kings in an abandoned mine. The other bandits make their way there as well. A mine gas explosion carries the rock with the treasure and the villains into the abyss. Albert frees his wife and learns of a huge inheritance from a distant relative. The French leave Africa.