In Biggles in Australia, Boller was the captain of the lugger Matilda and an active member of von Stalhein's espionage network in Australia.
Described as a large man with a black beard, Biggles first encountered Boller on the island where Toto Wada's body had been found. Biggles had returned to the island with Bill Gilson to identify the body but found that they had been forestalled--Boller had arrived first on board the Matilda and had sent his men to bury the body and remove all other evidence of the murders. While there, Boller had also attempted to ram Biggles' Otter amphibian with his lugger but was prevented by Ginger's quick action in taxying the aircraft away.
Back at Darwin, Biggles visited a local bar and there found an elderly mariner who was able to give him valuable background information on Boller. According to the mariner, Boller claimed to be a Dutchman but appeared to him more like a German. He had bought the Matilda from its previous Greek owner, Apergoulos and was presently involved in clearing a pandanus swamp at the head of the Daly River in order to grow peanuts. The mariner also described Boller as a man who was always looking for trouble, someone whom people would be happy to see go for good.
Towards the end of the book, Boller and other members of the espionage network were last seen sailing up to Daly Flats on the Matilda. Smith, Ivan and some others disembarked at Daly Flats and were attacked and killed by Australian aborigines but Boller and von Stalhein's bodies were not found. It was presumed that someone must have raised the alarm, leading Boller to turn his ship around to head for the open sea. The early arrival of the rainy season obstructed search efforts and allowed the ship to escape detection. Some weeks later, some wreckage was found on one of the Melville Islands which was believed to be that of the Matilda but this was not confirmed.