Chapter 1: A Noble Lord in TroubleEdit
Lord Phillip de Langdon of Ferndale asks Air-Commodore Raymond to help in a delicate case. A valuable collection of rubies has gone missing and he suspects an aircraft might be involved.
Raymond and Biggles go down to Ferndale Manor, Lord Langdon's residence. The initial facts do not look promising--Lord Langdon does not know when the theft took place--it could be a matter of months--it only came to his attention when he saw one of his rubies for sale at a jewellers in Bond Street.
Chapter 2: Lord Langdon Tells His StoryEdit
Langdon suspects the culprit might be his ex-footman, Richard Browning, who disappeared a few days ago after Langdon reprimanded him for being too familiar with his daughter, the teenaged Lady Caroline Langdon.
Chapter 3: The Lady CarolineEdit
The trail looks cold. Lady Caroline seems uncooperative--and perhaps even more puzzling, seems to be in cahoots with the thief for jewels which will some day be hers. However there is a slender clue--Langdon shows Biggles a photograph of Browning dresses in hunting gear standing over a leopard beside a bushman. Drawing on his wide geographic knowledge, Biggles surmises that the picture must have been taken in the Kalahari Desert.
Chapter 4: Biggles Makes Some CallsEdit
Further enquiries at the Mealing Flying Club nearby reveal that Browning took flying lessons there and that he took off in a Martin twin-engine aircraft. Surprisingly the Martin was not stolen--Browning bought it for cash (Biggles later discovers this is from the proceeds of the sale of a ruby).
Chapter 5: An Unexpected ClueEdit
Returning to Ferndale village, Biggles spots Lady Caroline emerging from a cottage not far from the manor. Enquiring at the village post office, Biggles learns that the cottage is the residence of Mrs Smith, a former nurse-maid at the manor. Suspecting a connection with Browning, Biggles probes further and learns that Mrs Smith recently received a letter with a foreign stamp, postmarked WIND---. Biggles surmises this could be Windhoek, the capital of South West Africa, where the part of the Kalahari is located. Browning must have gone there.
Chapter 6: The Trail Peters OutEdit
Biggles and Bertie take the Merlin and follow in Browning's tracks--which they soon find is a little too straightforward. Browning has gone down the west coast of Africa, stopping at the usual refueling stops, clearing formalities and paying for fuel in his real name. Arriving in Windhoek, Biggles finds that Browning did not call at any airports further south. From the airport manager and later from Bill Carter of the South West African police, Biggles learns that Browning may have gone into the Kalahari Desert with a partner named Mick Connor, a tough talking diamond prospector and hunter. It seems the local police are also interested in Connor's doings in the desert.
Chapter 7: The KalahariEdit
Biggles and Bertie begin a systematic search of the Kalahari for the Martin or for Connor's jeep.
Chapter 8: A Shot--From Where?Edit
On the fourth day, they come across a large fortified building. Returning to Windhoek from the building, they hear a sharp crack and discover on landing that they had been hit by a rifle bullet.
Chapter 9: Carter Has Some AnswersEdit
Carter tells them the building they saw must be Fort Schwarz, one of several forts built by the German troops at the time when they colonized South West Africa.
Chapter 10: Fort SchwarzEdit
Biggles and Bertie, believing that the shot must have come from Connor or Browning, return to the fort the next day. They find the fort apparently deserted but come across a pile of burnt out wreckage in a corner of the courtyard which turns out to be the remnants of the Martin. They also see a strange looking pile of rocks and, in a stable-like building, they meet a leopard chained to the wall.
Chapter 11: Mick ConnorEdit
They can´t do much more as Mick Connor returns and demands their business. Connor denies ever knowing Browning and so Biggles decides to leave. Getting into the Merlin, Bertie tells Biggles he thinks he saw a face looking out through an upper floor window.
Chapter 12: An Unexpected HazardEdit
Biggles takes the Merlin off but puts it down again as soon as he thinks he is out of earshot.
Chapter 13: Tense Work by MoonlightEdit
They return to the fort after dark for another look at the fort. Taking advantage of where the sand has piled up against the wall, Bertie lifts Biggles up onto the roof of the fort and Biggles begins a brief exploration, narrowly escaping discovery by Connor when the wooden stairway he is using collapses under him.
Chapter 14: Bertie Takes a ChanceEdit
They return to their aircraft and decide to wait until morning, planning to return to when they are sure Connor has left the fort.
Chapter 15: Browning Tells His TaleEdit
The next morning, Biggles sees Connor leaving on a jeep and so they make their way to the fort and find Browning in bed with a broken leg in an upper floor room. Browning tells them a surprising tale. Lord Langdon is actually his father from an earlier marriage and he had been born in South Africa. Lady Caroline is his half-sister. The rubies are not Lord Langdon's but Caroline's, having been left to her by her deceased mother. Browning had moved the rubies to prevent Langdon from squandering Caroline's inheritance as he had already wasted away most of his estate. Browning doesn't have the jewels himself but Lady Caroline knows where they are. Having moved the jewels, Browning then laid an obvious trail to make it appear he had taken them. He came back to the Kalahari to join Connor, a former hunting partner of his. However, after Connor had murdered a bushman,, they had fallen out and Browning decided to leave. Connor blocked his way and shot at Browning's aircraft as he tried to take off, causing it to crash. Since that time, he had been kep a virtual prisoner in the fort. Hearing the story, Biggles decides he is better off not knowing where the jewels are, otherwise he would be obliged to reveal it to Lord Langdon.
Chapter 16: Curtains for ConnorEdit
Biggles and Bertie decide to take Browning to Windhoek as he is badly in need of medical attention for his broke leg but they find their way blocked by Connor--he had appparently only left the fort as a ruse. The situation becomes tense but then they hear a twang and Connor collapses--he has been hit by a poison arrow shot by a bushman hiding somewhere in the fort--an act of revenge for the murder of his friend (whose body is under the mound of stones in the fort courtyard). Connor realises he is dying and passes a bag of diamonds to Browning, saying they are of no use to him now. They try to fly Connor to Windhoek but he dies on the way.
Chapter 17: A Family Hatchet is BuriedEdit
Returning to Britain, Biggles calls on Lord Langdon to tell him the brief facts, suggesting a reconciliation among the members of the family. He also speaks to Lady Caroline, telling her he has spoken to her brother and that he has a good idea where the rubies are--with Mrs Smith. Biggles suggests that she speak to her father about what has happened. Lady Caroline thanks Biggles for his help. Apologising for being unhelpful previously, she agrees with his suggestion.
Weeks later, Biggles hears from Browning--he had apparently come back to Ferndale Manor at the invitation of his father. The family is reconciled and they have all agreed to let bygones be bygones.