In The Case of the Modern Pirate, Father Antoinne was a French priest of the Sacre Coeur Mission who served the villages of the Kobe tribe on the northern coast of Papua New Guinea.
Biggles met the Father after he had found the wreck of the Cygnet, the ship which John Sebastian Blake and Nicholas Diaz had stolen. Father Antoinne told them that when the ship had been wrecked, he had been away at one of the outlying villages of his district. On his return, he had been told by the natives that most of the survivors had made their way through the Kobe territory, intending to travel south over the mountains to reach Port Moresby. Since they had to go through the territory of the hostile Gilkik tribe, he believed most of the sailors would have perished. However, two survivors had chosen to remain behind at a Kobe village for a while. During this time they were very often drunk and argumentative. During a scuffle, one of them had shot the other and had then fled into Gilkik territory. Father Antoinne had been shown the body of the dead man and by examining the letters in his pocket, had ascertained that his name was Blake. Following this, Diaz had been seen leading a number of Gilkik raids on the Kobe village.
While speaking to Biggles, Father Antoinne heard drums announcing the arrival of Biggles and his party. Biggles surmised that this might trigger yet another raid by Diaz and the Gilkiks since he would be more desperate than ever to get to the gold he had buried. Biggles, Ginger and Bertie therefore asked Father Antoinne to lead them to the Kobe village where they helped in the defence against the Gilkiks. This proved to be the final raid as Diaz was shot during the battle by a Kobe arrow. After the attackers had fled, Father Antoinne went forward to administer the last rites to Diaz. Knowing that he was dying, Diaz confessed the location of his hidden gold to the Father, allowing Biggles to complete his mission by recovering the gold which Blake and Diaz had stolen.