Prologue 1: "The King Has Spoken"[]
The first two chapters are set in 525 B.C. and provides the historical setting to the Biggles adventure. Hystomannus, the Captain of the Royal Guard tells his son that King Cambyses, against the advice of his commanders, has ordered his army to set out for the oasis of Siwah to sack the Temple of Ammon. Hystomannus is full of trepidation. "The enemies that we shall have to face will not be those of flesh and blood," he tells his son.
Prologue 2: The Desert Answers[]
The army of Cambyses moves into the desert. After three days, they are cheered to spot a range of hills but are engulfed by a sandstorm before they can reach it. Mazeus loses contact with the rest of the army in the storm but makes it to the hills. Believing that his father will soon come to search for him, he impales his lance vertically into the sand as a marker.
Chapter 1: The Moonlight Assassin[]
Biggles, Algy and Ginger stop by at Cairo on their way to Cape Town for a 266 Squadron reunion hosted by Major Mullen, Biggles' old C.O. Ginger takes an evening walk in the hotel garden and spots a figure creeping along the boundary wall. He yells a warning just as the man jumps up at a visitor who is just entering through the hotel's garden gate, thus saving the life of Kadar Alloui Bey from the would-be assassin. It turns out that Kadar has come to see Biggles. He wants to buy over Biggles' Tourer aircraft. Biggles is not inclined to sell but invites Kadar to tell his story.
Chapter 2: Kadar's Story[]
Kadar tells Biggles he wants to use the aircraft to search for a lost oasis, first spotted by Laslo Almazy and Sir Robert Clayton. The oasis may be related to the legend of Cambyses' Persian army which disappeared in the desert on their way from Khargah Oasis to Siwah. Kadar thinks the descendents of that army might well inhabit such a lost oasis. Kadar has found two clues himself: a stone inscription with Persian text, and a report by a Bedouin who told him he had spotted a lance of Persian design impaled vertically in the desert sand. However someone had recently stolen Kadar's notes, so the thieves now have the same clues and may well mount an expedition for themselves. Kadar needs an aircraft as a practical way of beating the thieves to the discovery. Biggles does not agree immediately but tells him he will think about it.
Chapter 3: Zarwan Calls[]
Another man, Fuad Zarwan calls. He tells Biggles to disregard the ramblings of Kadar whom he denounces as insane. He also attempts to warn Biggles off, telling him that in Egypt, vistors are well advised not to be inquisitive about matters which do not concern them. Characteristically, this has the precise opposite effect and Biggles decides to help Kadar.
Chapter 4: A Disconcerting Discovery[]
Biggles and his party fly out to set up an advance base at the uninhabited Semphis Oasis west of Khargah. There they discover that someone has punctured the main fuel tank of the Tourer. The hole is plugged but they do not have enough fuel to return to civilisation. They must hope that the caravan which is bringing most of their supplies arrives.
Chapter 5: The End of the Trail[]
The caravan is overdue. Desperate, Biggles and co. take off in search of it and find that it has been attacked and massacred. The fuel and supplies it carried are gone.
Chapter 6: The Haboob[]
Flying back to Semphis, they are caught in a haboob (sandstorm). Out of fuel and unable to see, they are forced to land, almost crashing into a range of mountains as they touch down.
Chapter 7: Lost in the Desert[]
They discover that they are in a wadi. Biggles believes that they may be near the spot of Kadar's lost oasis, and in any case they need to find water. Leaving Algy to guard the plane, Biggles and the rest set out to explore but become lost among the rocks and gullies. Finally, at the end of their endurance, they find a pool of water in a rocky fissure.
Chapter 8: The Tombs of the Dead[]
As night falls, Biggles decides they must try to find their way back to Algy. But stepping out of the cave, he finds his way block. A swarm of thousands of scorpions is approaching the mouth of the fissure, blocking his way. The only escape is a passage leading deeper into the cave. Braving attacks by bats, they finally emerge into a large hollow chamber. The sides are hollowed out with small cavities like a honeycomb. Kadar tells them they have found a tomb. One of the mummified corpses appears to be lying on the floor. It suddenly gets up and runs off. Then a large swarm of bats emerges from the passage heading for them. There is no choice. They run towards the far end of the chamber--the same way the mummified figure had gone. They see daylight ahead and finally emerge on the side of a steep hill.
Chapter 9: The Horror in the Pool[]
Down in the distance they see an oasis, with palm trees and fields of corn. A small hill rose up beyond with the ruins of a village on top. Kadar is of course excited about the discovery--it has to be the lost oasis. But Biggles is more worried about Algy. What would he do? Would he leave the plane to look for them? They decide the best plan is to go to the oasis to find food and water and then climb the cliff above the exit of the cave in an attempt to spot the location of their plane.
There are plentiful dates from the palms at the oasis and water from a large pond. Ginger dives in for a swim and here the obligatory encounter with a dangerous animal--here in the form of an enormous crocodile--occurs and Biggles has to haul him up just in time.
Refreshed, they get back to the cliffs and from the top they can see the palm tree they almost hit when landing. Armed with a map which Biggles draws, they make their way back through the cave to the plane. As feared, Algy is not there.
Chapter 10: Trapped[]
They wait through the day but there's no sign of Algy. Biggles decides they should go back to the oasis. So at nightfall, they leave a note for Algy in the plane and then set off.
Back at the oasis, Biggles notices fresh hoof marks which he had not seen the last time. Someone else has been here! They make their way up the hill to explore the ruined village. It turns out to be ringed by a defensive wall but they find the doorway and enter and start exploring the houses inside. As usual there's more dangerous animals, this time, poisonous snakes. But this isn't the only shock. Coming out of one house, they are surrounded by a large group of Tuareg and ... Zarwan!
The villain has them tied up on the ground and a trail of wild honey is laid over their bodies. It is "the torture of the ants", an ancient Egyptian custom.
Chapter 11: What Happened to Algy[]
The story rewinds to Algy who has been waiting anxiously for his comrades. It's a long wait and at nightfall, he hears something coming from the desert. From hiding, he sees that it is a caravan. But friend or foe? The members are Tuareg, and at the rear of the train, he spots several camels carrying loads of supplies. There is a camel which he recognised as one of those Kadar had bought. So these were the bandits who had attack Kadar's caravan and taken their supplies.
Algy follows the caravan at a distance until it stops and sets up a camp. Now he makes two astonishing discoveries. The precious petrol he would need for the plane is still around. The Tuareg are seen drinking it from cans and spitting it into the fire! Second, there's Zarwan!
Chapter 12: Algy to the Rescue[]
Algy follows the caravan. Along the way, he spots a lance thrust into the sand and takes it as a walking stick. At length, he reaches the oasis. There are Arabs by the water but Algy creeps forward nonetheless to get a drink. His plan is however upset when the crocodile emerges from the pond and grabs one of the Arabs. His companions react in horror and begin shooting at the beast. More Arabs rush down from the village up the hill.
Algy finds a piece of English newspaper. So Biggles must have been here and is probably up in the village exploring. So Algy makes a wide detour and climbs the hill on the far side, out of sight of the Arabs by the pond. He finds a breach in the village wall and climbs in and sees ... his comrades are tied to the ground and only three Tuareg--the rest must have run down to the pond.
With his rifle and finally the lance at close quarters, Algy despatches the three Tuareg and cuts Biggles, Kadar and Ginger free.
Chapter 13: Captured[]
Kadar is fascinated by Algy's lance. It's Persian, such as what Cambyses' army would have used. But there's no time for archaeology. The Tuareg at the oasis are streaming up to the village again, led by Zarwan. Our friends beat a hasty retreat through the breach in the wall that Algy found down to the oasis.
While the Tuareg are busy searching for them in the village, our friends make for the oasis where they find the petrol and start hiding it in a nearby hole in the sand. They just about finish the job when the Tuareg come back down the hill heading for them. Then, large numbers of men spring up from hiding all over and begin attacking the Tuareg. These men are different--dressed in armour and holding battle axes, swords and shields. It seems impossible but Kadar says it's Cambyses' Persian army!
The armoured warriors kill most of the Tuareg. Zarwan and a few surviving Tuareg are captured as are our friends. On to the scene comes the mummified figure they had met in the tombs. Up close they see she's an old woman. She waves and shrieks in an unknown language. The warriors seem to obey her and take their prisoners up the hill.
Chapter 14: A Hopeless Prospect[]
Our friends are locked up together in a cell in a large building at one end of the village. Kadar is convinced the warriors are Persians. When some of them come bearing food, he tries to communicated with them by writing words on his notebook. One of the warriors writes a few words in reply. Interpreted broadly, Kadar thinks they are to be sacrificed to the crocodile. As if to confirm this, that evening, they witness a procession with Zarwan being brought out to the oasis for just this ceremony.
Chapter 15: Condemned to the Crocodile[]
At sunset the next day, it's Biggles' turn but he has a plan. Brought to the water's edge, he begins to sing and dance, moving around until he gets to where they buried their cans of petrol. He uncovers 6 cans and then, still dancing, douses the warriors standing around him with petrol. The crocodile begins to move towards him so he quickly stuffs a third can into its jaws and then shoots the can with Algy's pistol. The petrol catches fire and jets of flame shoot out from the crocodile to ignite the fuel-soaked spectators nearby. There is pandemonium as the warriors flee in pain and fright. Biggles grabs 3 cans of petrol and escapes, heading for the cave entrance in the cliff face.
Chapter 16: Biggles Wins Through[]
The old woman spots Biggles escaping and rallies some troops to pursue him. Biggles tosses one of his cans at them and lights the streaming petrol with a match. There is yet another rain of fire which sends his pursuers retreating. Biggles waits till sunrise. Then he goes through the cave and reaches the plane. After refuelling it, he takes off.
Chapter 17: A Dreadful Sentence[]
Back in their cell, Algy, Ginger and Kadar attempt to make sense of what's been going on. Kadar theorises that the Tuareg had known about this oasis for some time. They came to trade with the old woman who, it seems, was one of the few willing to rob gemstones from the tombs. Zarwan probably profited from this trade by obtaining the gems from the Tuareg. Kadar's search for the oasis would have endangered the supply of gems trade, so Zarwan sabotaged the supply caravan and then by headed to the oasis to deal with Kadar himself. Why did the old woman fetch the warriors and turn against Zarwan? Perhaps she thought Zarwan had led Biggles and co. to the oasis and thus had double-crossed her.
From their cell, they see the inferno Biggles had triggered at the oasis and the stream of fire at the cliff as he fought off his pursuers. They are cheered that he got away but now some more warriors enter the room. They appear burned and bruised and obviously in a foul mood. They take no chances. Algy, Ginger and Kadar are bound hand and foot and taken up the cliff to the cave, there to be buried alive.
Chapter 18: Biggles Strikes[]
Once in the air, Biggles heads for the oasis. He sees the procession of warriors carrying Algy, Ginger and Kadar and buzzes the group, firing flares from his signalling pistol. The warriors scatter in fright. Biggles lands and cuts his comrades free. They dig up all the remaining cans of petrol and refuel the plane. There is just enough, Biggles thinks, to get to Siwah.
Near them, they spot a body. It's the old woman and she appears to have died falling off the cliff. There's a bag of jewels on her so Biggles takes it. The warriors are beginning to rally, so, with the refuelling complete, they take off.
Chapter 19: Mirage![]
The Tourer heads for Siwah. They are deceived a few times by mirages but make it to the oasis on the last of their petrol.
Chapter 20: Farewell to the Desert[]
Kadar's father is at Siwah. One Arab of Kadar's caravan had survived Zarwan's attack and had ridden to Siwah with the news. Kadar's father had flown to Siwah to organise search parties for them. He sends to Mersa Matruh for petrol for the Tourer. This arrives after after three weeks. Our friends continue to Cairo where they attend a grand reception. They are amply rewarded for the jewels they had recovered. Kadar is appointed the honorary curator of a museum. But Algy reminds Biggles that they were on their way to South Africa and so they depart, with just enough time to make it for the dinner.