In Biggles Works It Out, Count Heinrich Horndorf was the master criminal and leader of a criminal gang known as "The White Prophets of Peace" which maintained a secret base in the desert oasis of El Asile. The Count reisded in a luxurious but heavily guarded villa, the Villa Hirondelle near the mountain town of Eze in the south of France.
When Dick Canton spotted Bertie as a potential pilot for the gang, Bertie was brought before the Count for an interview. The Count, seen through Bertie's eyes, became the subject of another one of Johns' vivid word pictures. He was all, broad-shouldered and about sixty, carrying his "corpulence with the dignity of those years." His face was described as square, with "features so ruggedly prominent that they might have been hacked out of wood." There were little bags under his eyes and his jaw muscles were beginning to sag, suggesting for Bertie that the Count led a life of self-indulgence.
After questioning Bertie aboout his flying experience and a veiled warning about the consequences of betrayal, Bertie was formally inducted into the gang, with the Count paying him a large sum of French money (which turned out later to be counterfeit).
Bertie had observed that in any walk of life, a man like the Count was someone to be reckoned with and this turned out to be true. The Count took little part in the plot of the book but whenever members of the gang mentioned him, they all seemed afraid to offend him. When von Stalhein found out about Bertie's recruitment and told Nick Canton, Groot and Luis Leguez that they had made a big mistake and recruited one of Biggles' men, all present, including von Stalhein himself, were extremely reluctant to break the bad news to the Count and preferred to settle the problem by themselves.
Towards the end of the book, the Villa Hirondelle was raided by the French police. Papers found in the safe showed that the Count was actually one Jacob Theller, a master printer who had helped Hitler forge currency notes for use in the countries he occupied and wanted by the police for his war crimes. The Count was not at the Villa during the raid. He had escaped in an aircraft piloted by Luis Leguez. Some weeks later, the wreckage of the aircraft was found on a Swiss mountainside with the bodies of Leguez and Theller on board. In Theller's valise were found counterfeit currency notes of several European countries as well as the plates they were printed from. In a false bottom of his valise were found jewels from several robberies which his gang had conducted.