In Murder by Thirst, John Murray, of Kalgoorlie, Western Australia, was one of two students who traveled to London to complete their music studies at the London School of Music.
While flying from Darwin to London, John, and his partner Sally Dunn had spotted Black Jack Barnes on the same flight. John and Sally's suspicions were aroused because Barnes, who had a bad reputation, had gone missing while out prospecting for gold in the Western Australian desert several weeks before and had not been found after an extensive air search.
For John and Sally, there were many unanswered questions. What had happened to his partner, the novice British prospector Mr Farlow? If Barnes had found gold, why had he not registered a claim? John speculated that Barnes may have murdered his partner Farlow after finding a large deposit of gold. As the strike would be too big to handle, he had traveled to Britain to interest one of the large mining companies. He had to come to London as Australian companies would know of his reputation and in any case would have asked questions about his partner Farlow. John and Sally had discussed the matter in detail and, having read about Biggles, decided to tell him about their suspicions. Biggles was impressed by their sound reasoning and decided to take up the case.